Cleaning systems for additive manufacturing apparatuses and methods for using the same

ABSTRACT

Embodiments of the present disclosure are directed to additive manufacturing apparatuses, cleaning stations incorporated therein, and methods of cleaning using the cleaning stations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalApplication Ser. No. 62/852,034, titled “CLEANING SYSTEMS FOR ADDITIVEMANUFACTURING APPARATUSES AND METHODS FOR USING THE SAME” filed May 23,2019, the entire contents of which are hereby incorporated by reference.

BACKGROUND Field

The present specification generally relates to additive manufacturingapparatuses and, more specifically, to cleaning systems for additivemanufacturing apparatuses and methods for using the same.

Technical Background

Additive manufacturing apparatuses may be utilized to “build” an objectfrom build material, such as organic or inorganic powders, in alayer-wise manner. Early iterations of additive manufacturingapparatuses were used for prototyping three-dimensional (3D) parts.However, as additive manufacturing technology has improved, there is anincreased interest in utilizing additive manufacturing apparatuses forlarge-scale commercial production of parts. One issue of scalingadditive manufacturing apparatuses to commercial production is improvingthe through-put of additive manufacturing apparatuses to meet commercialdemands.

Accordingly, a need exists for alternative additive manufacturingapparatuses and components thereof which improve manufacturingthrough-put.

SUMMARY

A first aspect A1, a cleaning station for an additive manufacturingsystem, wherein the cleaning station comprises a cleaning station vesselcomprising a wet wipe cleaner section and a dry wipe cleaner sectiondownstream of the wet wiper section, wherein: the wet wipe cleanersection comprises a wet wipe member coupled to an actuator, the actuatorbeing operable to vertically raise and lower the wet wipe member intothe cleaning station vessel; and the dry wipe cleaner section comprisesa dry wipe member coupled to an actuator, the actuator being operable tovertically raise and lower the dry wipe member into the cleaning stationvessel, wherein the wet wipe cleaner section and the dry wipe cleanersection are arranged sequentially such that the wet wipe member isconfigured to apply cleaning fluid to a print head and the dry wipemember is configured to remove excess cleaning fluid from the print headafter cleaning by the wet wipe cleaner section.

A second aspect A2 includes the cleaning station of aspect A1, furthercomprising a capping section operable to maintain a print head in a wetstate when the print head is idle.

A third aspect A3 includes the cleaning station of aspect A2, whereinthe capping section comprises a sponge coupled to an actuator, theactuator being operable to vertically raise and lower the sponge intothe cleaning station vessel.

A fourth aspect A4 includes the cleaning station of aspect A3, whereinat least a portion of the sponge extends above a fluid level of thecleaning fluid.

A fifth aspect A5 includes the cleaning station of aspect A2, whereinthe capping section is coupled to an actuator operable to verticallyraise and lower the capping section into the cleaning station vessel.

A sixth aspect A6 includes the cleaning station of any of the foregoingaspects A1-A5, wherein the cleaning station vessel comprises a pluralityof inlet ports located within the cleaning station vessel to circulatethe cleaning fluid within the cleaning station vessel and a drainlocated within the cleaning station vessel through which contaminantsand cleaning fluid exit the cleaning station vessel.

A seventh aspect A7 includes the cleaning station of any of theforegoing aspects A1-A6, wherein the cleaning station vessel is in fluidcommunication with an overflow vessel comprising a first fluid levelsensor and a second fluid level sensor, wherein cleaning fluid is pumpedout of the overflow vessel responsive to the first fluid level sensorand the second fluid level sensor detecting the cleaning fluid untilneither of the first fluid level sensor and the second fluid levelsensor detects the cleaning fluid.

An eighth aspect A8 is directed to method of cleaning a print head usedin an additive manufacturing system, the additive manufacturing systemcomprising a cleaning station and a build platform, wherein the cleaningstation comprises a binder purge bin and a cleaning station vesselcomprising a wet wipe cleaner section, and a dry wipe cleaner section,wherein the cleaning station vessel comprises cleaning fluid, andwherein the method comprises: passing the print head over the binderpurge bin to facilitate discharge of contaminants from the print headvia backpressure; introducing the print head to the wet wipe cleanersection so that cleaning fluid is applied to the print head by a wetwipe member; and introducing the print head to the dry wipe cleanersection so that cleaning fluid is removed by a dry wipe member and theprint head is thereby cleaned.

A ninth aspect A9 includes the method of aspects A8, further comprisingintroducing the print head to an additional purge bin downstream of thedry wipe cleaner section and upstream of the build platform.

A tenth aspect A10 includes the method of any of the foregoing aspectsA8-A9, wherein the dry wipe member is vertically raised out of thecleaning fluid before completion of discharge of contaminants from theprint head.

An eleventh aspect A11 includes the method of any of the foregoingaspects A8-A10, wherein the wet wipe member is vertically raised out ofthe out of the cleaning fluid when discharge of contaminants from theprint head is complete.

A twelfth aspect A12 includes the method of any of the foregoing aspectsA8-A11, wherein excess binder is discharged into the binder purge binwhile a recoat head is operating in a direction supplying build materialto a working surface of the build platform.

A thirteenth aspect A13 includes the method of any of the foregoingaspects A8-A12, wherein the steps of introducing the print head to thewet wipe cleaner section and introducing the print head to the dry wipecleaner section are performed while a recoat head is traveling in adirection from the build platform toward a recoat home position.

A fourteenth aspect A14 includes the method of any of the foregoingaspects A8-A13, further comprising removing cleaning fluid from thecleaning station vessel if a fluid level of cleaning fluid exceeds amaximum fluid level.

A fifteenth aspect A15 includes the method of any of the foregoingaspects A8-A14, further comprising adjusting one or more components ofthe cleaning station, the adjusting comprising: adjusting a verticalposition of one or more of a top edge of the wet wipe member and a topedge of the dry wipe member to a position such that the one or more ofthe top edge of the wet wipe member and the top edge of the dry wipemember is vertically lower than a first section of a height gauge havinga first vertical position and vertically higher than a second section ofthe height gauge having a second vertical position; wherein the heightgauge is affixed to a print head assembly comprising the print head.

A sixteenth aspect A16 includes the method of any of the foregoingaspects A8-A15, further comprising: prior to passing the print head overthe binder purge bin, introducing the print head to at least one of thedry wipe cleaner section and the wet wipe cleaner section to pre-cleanthe print head.

A seventeenth aspect A17 includes the method of any of the foregoingaspects A8-A16, further comprising: introducing the print head to apurge wipe member after the discharge of contaminants from the printhead so that binder fluid discharged from the print head with thecontaminants are wiped from a face of the print head prior tointroducing the print head to the wet wipe cleaner section.

An eighteenth aspect A18 is directed to a method for storing a printhead comprising: applying cleaning fluid to the print head using a wetwipe member; removing cleaning fluid from the print head using a drywipe member; and applying a cover to the print head to create anon-curing environment around the print head.

A nineteenth aspect A19 includes the method of aspect A18, whereinapplying the cover comprises actuating an actuator coupled to a wetsponge to raise the wet sponge within a cleaning station vessel intocontact with the print head.

A twentieth aspect A20 includes the method of aspect A18, whereinapplying the cover comprises bringing the print head into contact with acleaning vessel containing the cleaning fluid to maintain a humiditylevel between the print head and the cleaning vessel.

Additional features and advantages of the additive manufacturingapparatuses described herein, and the components thereof, will be setforth in the detailed description which follows, and in part will bereadily apparent to those skilled in the art from that description orrecognized by practicing the embodiments described herein, including thedetailed description which follows, the claims, as well as the appendeddrawings.

It is to be understood that both the foregoing general description andthe following detailed description describe various embodiments and areintended to provide an overview or framework for understanding thenature and character of the claimed subject matter. The accompanyingdrawings are included to provide a further understanding of the variousembodiments, and are incorporated into and constitute a part of thisspecification. The drawings illustrate the various embodiments describedherein, and together with the description serve to explain theprinciples and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts an additive manufacturing apparatusaccording to one or more embodiments shown and described herein;

FIG. 2 schematically depicts an embodiment of an actuator assembly foran additive manufacturing apparatus according to one or more embodimentsshown and described herein;

FIG. 3A is a schematic top view of a cleaning station of an additivemanufacturing apparatus according to one or more embodiments shown anddescribed herein;

FIG. 3B is a side cross-sectional view of a cleaning station of anadditive manufacturing apparatus according to one or more embodimentsshown and described herein;

FIG. 3C is a side cross-sectional view of a cleaning station vessel ofan additive manufacturing apparatus according to one or more embodimentsshown and described herein;

FIG. 4A is a schematic perspective view of a wet wipe member includingtwo blades in a wet wipe cleaning section of an additive manufacturingapparatus according to one or more embodiments shown and describedherein;

FIG. 4B is a cross-sectional front view of a wet wipe member in a wetwipe cleaning section of an additive manufacturing apparatus accordingto one or more embodiments shown and described herein;

FIG. 4C is a schematic perspective view of a wet wipe member including asingle blade in a wet wipe cleaning section of an additive manufacturingapparatus according to one or more embodiments shown and describedherein;

FIG. 4D is a cross-sectional front view of a wet wipe member in a wetwipe cleaning section of an additive manufacturing apparatus accordingto one or more embodiments shown and described herein;

FIG. 4E is a cross-sectional side view of a blade-less wet wipe memberin a wet wipe cleaning section of an additive manufacturing apparatusaccording to one or more embodiments shown and described herein;

FIG. 4F is a cross-sectional side view of a vacuum wipe member in a wetwipe cleaning section of an additive manufacturing apparatus accordingto one or more embodiments shown and described herein;

FIG. 4G is a cross-sectional side view of a wet wipe member includingtwo blades having different vertical positions in a wet wipe cleaningsection of an additive manufacturing apparatus according to one or moreembodiments shown and described herein;

FIG. 5A is a top view of an angled dry wipe member in a dry wipecleaning section of an additive manufacturing apparatus according to oneor more embodiments shown and described herein;

FIG. 5B is a partial top view of FIG. 5A without the angled wipersincluded for illustration according to one or more embodiments shown anddescribed herein;

FIG. 5C is a cross-sectional front view of the wiper mounting member ofthe dry wipe member according to one or more embodiments shown anddescribed herein;

FIG. 5D is a cross-sectional front view of the wiper mounting memberincluding blades at different vertical positions of the dry wipe memberaccording to one or more embodiments shown and described herein;

FIG. 6A is a cross-sectional front view of a dry wipe member submergedin cleaning fluid in the dry wipe section of the cleaning station vesselaccording to one or more embodiments shown and described herein;

FIG. 6B is a cross-sectional front view depicting one end of the drywipe member of FIG. 6A raised above the fluid level of the cleaningfluid according to one or more embodiments shown and described herein;

FIG. 6C is a cross-sectional front view depicting both ends of the drywipe member of FIG. 6A raised above the fluid level of the cleaningfluid according to one or more embodiments shown and described herein;

FIG. 6D is a cross-sectional front view depicting one end of the wetwipe member of FIG. 6A raised above the fluid level of the cleaningfluid according to one or more embodiments shown and described herein;

FIG. 6E is a cross-sectional front view depicting both ends of the wetwipe member of FIG. 6A raised above the fluid level of the cleaningfluid according to one or more embodiments shown and described herein;

FIG. 6F is a cross-sectional front view depicting an adjustable hardstop for use in coupling of one of the members of the cleaning stationwithin the cleaning station vessel according to one or more embodimentshown and described herein;

FIG. 7A is a cross-sectional side view of a capping section of thecleaning station including a sponge according to one or more embodimentsshown and described herein;

FIG. 7B is a cross-sectional side view of a capping section of thecleaning station including a cap according to one or more embodimentsshown and described herein;

FIG. 7C is a cross-sectional front view of a cleaning station in whichthe cleaning station vessel is actuated vertically to cover the printhead according to one or more embodiments shown and described herein;

FIG. 7D is a cross-sectional front view of a cleaning station in whichseals around the cleaning station vessel are actuated vertically tocover the print head according to one or more embodiments shown anddescribed herein;

FIG. 7E is a cross-sectional front view of a cleaning station in whichthe cleaning station vessel includes deflated seals according to one ormore embodiments shown and described herein;

FIG. 7F is a cross-sectional front view of a cleaning station in whichthe deflated seals of FIG. 7E are inflated to form a seal with the printhead according to one or more embodiments shown and described herein;

FIG. 8 is a process flow diagram of the fluid management system (binderpathway and the cleaning fluid pathway) according to one or moreembodiments shown and described herein;

FIG. 9 is a flow chart depicting an embodiment of cleaning fluidmaintenance according to one or more embodiments shown and describedherein;

FIG. 10 schematically depicts a control system for controlling thecomponents of the binder pathway and the cleaning fluid pathwayaccording to one or more embodiments shown and described herein; and

FIG. 11 is a cross-sectional side view of a print head having a gaugethereon for use in setting a maximum vertical height of one or morecomponents of the cleaning station according to one or more embodimentsshown and described herein.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of additivemanufacturing apparatuses, and components thereof, examples of which areillustrated in the accompanying drawings. Whenever possible, the samereference numerals will be used throughout the drawings to refer to thesame or like parts. One embodiment of an additive manufacturingapparatus 100 comprising a cleaning station 110 is schematicallydepicted in FIG. 1. The cleaning station 110 may generally include a wetwipe cleaner section and a dry wipe cleaner section. The cleaningstation is in fluid communication with a cleaning fluid reservoir andapplies cleaning fluid to a print head to clean the print head. Variousembodiments of cleaning stations for additive manufacturing apparatuses,additive manufacturing apparatus comprising the cleaning stations, andmethods for using the same are described in further detail herein withspecific reference to the appended drawings.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. Itwill be further understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint.

Directional terms as used herein - for example up, down, right, left,front, back, top, bottom—are made only with reference to the figures asdrawn and are not intended to imply absolute orientation unlessotherwise expressly stated.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order, nor that with any apparatus specificorientations be required. Accordingly, where a method claim does notactually recite an order to be followed by its steps, or that anyapparatus claim does not actually recite an order or orientation toindividual components, or it is not otherwise specifically stated in theclaims or description that the steps are to be limited to a specificorder, or that a specific order or orientation to components of anapparatus is not recited, it is in no way intended that an order ororientation be inferred, in any respect. This holds for any possiblenon-express basis for interpretation, including: matters of logic withrespect to arrangement of steps, operational flow, order of components,or orientation of components; plain meaning derived from grammaticalorganization or punctuation, and; the number or type of embodimentsdescribed in the specification.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to “a” component includes aspects having two or moresuch components, unless the context clearly indicates otherwise.

During operation of an additive manufacturing apparatus, the efficacyand performance of the print head is essential. The print head isexposed to heat, and is also subject to excess build materialdistributed by a recoat head and/or binder material from the print head.The combination of these contaminants (i.e., excess build material andbinder material) can lead to clogged nozzles in the print head, whichcan adversely impact operation of the additive manufacturing apparatus.

The embodiments described herein are directed to additive manufacturingapparatuses and components for additive manufacturing apparatuses,specifically cleaning systems in additive manufacturing apparatuses,which may be used to conduct automated routine maintenance of theadditive manufacturing apparatuses to reduce or eliminate the presenceof clogged nozzles in the print head and other contamination.

Additive Manufacturing Apparatus

Referring now to FIG. 1, an embodiment of an additive manufacturingapparatus 100 is schematically depicted. The additive manufacturingapparatus 100 includes a cleaning station 110, a build platform 120, andan actuator assembly 102. The additive manufacturing apparatus 100 mayoptionally include a supply platform 130. The actuator assembly 102comprises, among other elements, a recoat head 140 for distributingbuild material 400 and a print head 150 for depositing binder material500. The actuator assembly 102 may be constructed to facilitateindependent control of the recoat head 140 and the print head 150 alongthe working axis 116 of the additive manufacturing apparatus 100. Thisallows for the recoat head 140 and the print head 150 to traverse theworking axis 116 of the additive manufacturing apparatus 100 in the samedirection and/or in opposite directions and for the recoat head 140 andthe print head 150 to traverse the working axis of the additivemanufacturing apparatus 100 at different speeds and/or the same speed.Independent actuation and control of the recoat head 140 and the printhead 150, in turn, allows for at least some steps of the additivemanufacturing process to be performed simultaneously thereby reducingthe overall cycle time of the additive manufacturing process to lessthan the sum of the cycle time for each individual step. In theembodiments of the additive manufacturing apparatus 100 describedherein, the working axis 116 of the additive manufacturing apparatus 100is parallel to the +/−X axis of the coordinate axes depicted in thefigures.

In the embodiment depicted in FIG. 1, the additive manufacturingapparatus 100 includes a cleaning station 110, a build platform 120, asupply platform 130, and an actuator assembly 102. However, it should beunderstood that, in other embodiments, the additive manufacturingapparatus 100 does not include a supply platform 130, such as inembodiments where build material is supplied to the build platform 120with, for example and without limitation, a build material hopper. Inthe embodiment depicted in FIG. 1, the cleaning station 110, the buildplatform 120, and the supply platform 130 are positioned in series alongthe working axis 116 of the additive manufacturing apparatus 100 betweena print home position 158 of the print head 150 located proximate an endof the working axis 116 in the −X direction, and a recoat home position148 of the recoat head 140 located proximate an end of the working axis116 in the +X direction. That is, the print home position 158 and therecoat home position 148 are spaced apart from one another in ahorizontal direction that is parallel to the +/−X axis of the coordinateaxes depicted in the figures and the cleaning station 110, the buildplatform 120, and the supply platform 130 are positioned therebetween.In the embodiments described herein, the build platform 120 ispositioned between the cleaning station 110 and the supply platform 130along the working axis 116 of the additive manufacturing apparatus 100.

The cleaning station 110 is positioned proximate one end of the workingaxis 116 of the additive manufacturing apparatus 100 and is co-locatedwith the print home position 158 where the print head 150 is located or“parked” before and after depositing binder material 500 on a layer ofbuild material 400 positioned on the build platform 120. The cleaningstation 110 may include one or more cleaning sections (shown in greaterdetail below) to facilitate cleaning the print head 150 betweendepositing operations.

The build platform 120 is coupled to a lift system comprising a buildplatform actuator 122 to facilitate raising and lowering the buildplatform 120 relative to the working axis 116 of the additivemanufacturing apparatus 100 in a vertical direction (i.e., a directionparallel to the +/−Z directions of the coordinate axes depicted in thefigures). The build platform actuator 122 may be, for example andwithout limitation, a mechanical actuator, an electro-mechanicalactuator, a pneumatic actuator, a hydraulic actuator, or any otheractuator suitable for imparting linear motion to the build platform 120in a vertical direction. Suitable actuators may include, withoutlimitation, a worm drive actuator, a ball screw actuator, a pneumaticpiston, a hydraulic piston, an electro-mechanical linear actuator, orthe like. The build platform 120 and build platform actuator 122 arepositioned in a build receptacle 124 located below the working axis 116(i.e., in the −Z direction of the coordinate axes depicted in thefigures) of the additive manufacturing apparatus 100. During operationof the additive manufacturing apparatus 100, the build platform 120 isretracted into the build receptacle 124 by action of the build platformactuator 122 after each layer of binder material 500 is deposited on thebuild material 400 located on build platform 120.

The supply platform 130 is coupled to a lift system comprising a supplyplatform actuator 132 to facilitate raising and lowering the supplyplatform 130 relative to the working axis 116 of the additivemanufacturing apparatus 100 in a vertical direction (i.e., a directionparallel to the +/−Z directions of the coordinate axes depicted in thefigures). The supply platform actuator 132 may be, for example andwithout limitation, a mechanical actuator, an electro-mechanicalactuator, a pneumatic actuator, a hydraulic actuator, or any otheractuator suitable for imparting linear motion to the supply platform 130in a vertical direction. Suitable actuators may include, withoutlimitation, a worm drive actuator, a ball screw actuator, a pneumaticpiston, a hydraulic piston, an electro-mechanical linear actuator, orthe like. The supply platform 130 and supply platform actuator 132 arepositioned in a supply receptacle 134 located below the working axis 116(i.e., in the −Z direction of the coordinate axes depicted in thefigures) of the additive manufacturing apparatus 100. During operationof the additive manufacturing apparatus 100, the supply platform 130 israised relative to the supply receptacle 134 and towards the workingaxis 116 of the additive manufacturing apparatus 100 by action of thesupply platform actuator 132 after a layer of build material 400 isdistributed from the supply platform 130 to the build platform 120, aswill be described in further detail herein.

Referring now to FIGS. 1 and 2, FIG. 2 schematically depicts theactuator assembly 102 of the additive manufacturing apparatus 100 ofFIG. 1. The actuator assembly 102 generally comprises the recoat head140, the print head 150, a recoat head actuator 144, a print headactuator 154, an upper support 182, and a lower support 184. In theembodiments described herein, the upper support 182 and the lowersupport 184 extend in a horizontal direction (i.e., a direction parallelto the +/−X direction of the coordinate axes depicted in the figures)parallel to the working axis 116 (FIG. 1) of the additive manufacturingapparatus 100 and are spaced apart from one another in the verticaldirection (i.e., a direction parallel to the +/−Z direction of thecoordinate axes depicted in the figures). When the actuator assembly 102is positioned over the cleaning station 110, the build platform 120, andthe supply platform 130 as depicted in FIG. 1, the upper support 182 andthe lower support 184 extend in a horizontal direction from at least thecleaning station 110 to beyond the supply platform 130.

In one embodiment, such as the embodiment of the actuator assembly 102depicted in FIGS. 1 and 2, the upper support 182 and the lower support184 are opposite sides of a rail 180 that extends in a horizontaldirection and is oriented such that the upper support 182 is positionedabove and spaced apart from the lower support 184. For example, in oneembodiment, the rail 180 may be rectangular or square in vertical crosssection (i.e., a cross section in the Y-Z plane of the coordinate axesdepicted in the figures) with the top and bottom surfaces of therectangle or square forming the upper support 182 and the lower support184, respectively. In an alternative embodiment (not depicted), the rail180 may have an “I” configuration in vertical cross section (i.e., across section in the Y-Z plane of the coordinate axes depicted in thefigures) with the upper and lower flanges of the “I” forming the uppersupport 182 and the lower support 184, respectively. However, it shouldbe understood that other embodiments are contemplated and possible. Forexample and without limitation, the upper support 182 and the lowersupport 184 may be separate structures, such as separate rails,extending in the horizontal direction and spaced apart from one anotherin the vertical direction as depicted in an alternative embodiment ofthe actuator assembly.

In the embodiments described herein, the recoat head actuator 144 iscoupled to one of the upper support 182 and the lower support 184 andthe print head actuator 154 is coupled to the other of the upper support182 and the lower support 184 such that the recoat head actuator 144 andthe print head actuator 154 are arranged in a “stacked” configuration.For example, in the embodiment of the actuator assembly 102 depicted inFIGS. 1 and 2, the recoat head actuator 144 is coupled to the lowersupport 184 and the print head actuator 154 is coupled to the uppersupport 182. However, it should be understood that, in other embodiments(not depicted) the recoat head actuator 144 may be coupled to the uppersupport 182 and the print head actuator 154 may be coupled to the lowersupport 184.

In the embodiments described herein, the recoat head actuator 144 isbi-directionally actuatable along a recoat motion axis 146 and the printhead actuator 154 is bi-directionally actuatable along a print motionaxis 156. That is, the recoat motion axis 146 and the print motion axis156 define the axes along which the recoat head actuator 144 and theprint head actuator 154 are actuatable, respectively. The recoat motionaxis 146 and the print motion axis 156 extend in a horizontal directionand are parallel with the working axis 116 (FIG. 1) of the additivemanufacturing apparatus 100. In the embodiments described herein, therecoat motion axis 146 and the print motion axis 156 are parallel withone another and spaced apart from one another in the vertical directiondue to the stacked configuration of the recoat head actuator 144 and theprint head actuator 154. In some embodiments, such as the embodiment ofthe actuator assembly 102 depicted in FIG. 2, the recoat motion axis 146and the print motion axis 156 are located in separate vertical planes(i.e., a plane parallel to the X-Z plane of the coordinate axes depictedin the figures). However, it should be understood that other embodimentsare contemplated and possible, such as embodiments in which the recoatmotion axis 146 and the print motion axis 156 are located in the samevertical plane.

In the embodiments described herein, the recoat head actuator 144 andthe print head actuator 154 may be, for example and without limitation,mechanical actuators, electro-mechanical actuators, pneumatic actuators,hydraulic actuators, or any other actuator suitable for providing linearmotion. Suitable actuators may include, without limitation, worm driveactuators, ball screw actuators, pneumatic pistons, hydraulic pistons,electro-mechanical linear actuators, or the like. In one particularembodiment, the recoat head actuator 144 and the print head actuator 154are linear actuators manufactured by Aerotech® Inc. of Pittsburgh, Pa.,such as the PRO225LM Mechanical Bearing, Linear Motor Stage.

As shown in FIGS. 1 and 2, the recoat head 140 is coupled to the recoathead actuator 144 such that the recoat head 140 is positioned below(i.e., in the −Z direction of the coordinate axes depicted in thefigures) the upper support 182 and the lower support 184. When theactuator assembly 102 is assembled over the cleaning station 110, thebuild platform 120, and the supply platform 130 as depicted in FIG. 1,the recoat head 140 is situated on the working axis 116 (FIG. 1) of theadditive manufacturing apparatus 100. Thus, bi-directional actuation ofthe recoat head actuator 144 along the recoat motion axis 146 affectsbi-directional motion of the recoat head 140 on the working axis 116 ofthe additive manufacturing apparatus 100. In the embodiment of theactuator assembly 102 depicted in FIGS. 1 and 2, the recoat head 140 iscoupled to the recoat head actuator 144 with support bracket 176 suchthat the recoat head 140 is positioned on the working axis 116 (FIG. 1)of the additive manufacturing apparatus 100 while the recoat headactuator 144 is positioned above the working axis 116. Positioning therecoat head actuator 144 above the working axis 116 of the additivemanufacturing apparatus 100 reduces fouling of the recoat head actuator144 with powder from either the build platform 120 or the supplyplatform 130. This increases the maintenance interval for the recoathead actuator, increases the service life of the recoat head actuator,reduces machine downtime, and reduces build errors due to fouling of therecoat head actuator 144. In addition, positioning the recoat headactuator 144 above the working axis 116 of the additive manufacturingapparatus 100 allows for improved visual and physical access to thebuild platform 120 and the supply platform 130, improving the ease ofmaintenance and allowing for better visual observation (from humanobservation, camera systems, or the like) of the additive manufacturingprocess. In some embodiments described herein, the recoat head 140 maybe fixed in directions orthogonal to the recoat motion axis 146 and theworking axis 116 (i.e., fixed along the +/−Z axis and/or fixed along the+/−Y axis).

Similarly, the print head 150 is coupled to the print head actuator 154such that the print head 150 is positioned below (i.e., in the −Zdirection of the coordinate axes depicted in the figures) the uppersupport 182 and the lower support 184. When the actuator assembly 102 isassembled over the cleaning station 110, the build platform 120, and thesupply platform 130 as depicted in FIG. 2, the print head 150 issituated on the working axis 116 (FIG. 2) of the additive manufacturingapparatus 100. Thus, bi-directional actuation of the print head actuator154 along the print motion axis 156 affects bi-directional motion of theprint head 150 on the working axis 116 of the additive manufacturingapparatus 100. In the embodiment of the actuator assembly 102 depictedin FIG. 2, the print head 150 is coupled to the print head actuator 154with support bracket 174 such that the print head 150 is positioned onthe working axis 116 (FIG. 2) of the additive manufacturing apparatus100 and the print head actuator 154 is positioned above the working axis116. Positioning the print head actuator 154 above the working axis 116of the additive manufacturing apparatus 100 reduces fouling of the printhead actuator 154 with powder from either the build platform 120 or thesupply platform 130. This increases the maintenance interval for theprint head actuator 154, increases the service life of the print headactuator 154, reduces machine downtime, and reduces build errors due tofouling of the print head actuator 154. In addition, positioning theprint head actuator 154 above the working axis 116 of the additivemanufacturing apparatus 100 allows for improved visual and physicalaccess to the build platform 120 and the supply platform 130, improvingthe ease of maintenance and allowing for better visual observation (fromhuman observation, camera systems, or the like) of the additivemanufacturing process. In some embodiments described herein, the printhead 150 may be fixed in directions orthogonal to the print motion axis156 and the working axis 116 (i.e., fixed along the +/−Z axis and/orfixed along the +/−Y axis). That is, in embodiments, the entire printhead is fixed in directions orthogonal to the print motion axis 156,however, sub-components of the print head, such individual arrays ofnozzles or the like, may be translatable in directions that arenon-parallel to the print motion axis 156, such as directions that areorthogonal to the print motion axis.

As noted above, in the embodiments described herein the recoat head 140and the print head 150 are both located on the working axis 116 of theadditive manufacturing apparatus 100. As such, the movements of therecoat head 140 and the print head 150 on the working axis 116 occuralong the same axis and are thus co-linear. With this configuration, therecoat head 140 and the print head 150 may occupy the same space (orportions of the same space) along the working axis 116 of the additivemanufacturing apparatus 100 at different times during a single buildcycle. However, the recoat motion axis 146 of the recoat head actuator144 and the print motion axis 156 of the print head actuator 154 arespaced apart from one another in a vertical direction due to the stackedconfiguration of the actuators 144, 154. The spacing of the recoatmotion axis 146 and the print motion axis 156 permits the recoat head140 and the print head 150 to be moved along the working axis 116 of theadditive manufacturing apparatus 100 simultaneously in a coordinatedfashion, in the same direction and/or in opposing directions, at thesame speeds or different speeds. This, in turn, allows for individualsteps of the additive manufacturing process, such as the distributingstep (also referred to herein as the recoating step), the depositingstep (also referred to herein as the printing step), the curing (orheating) step, and/or the cleaning step to be performed with overlappingcycle times. For example, the distributing step may be initiated whilethe cleaning step is being completed; the depositing step may beinitiated while the distributing step in completed; and/or the cleaningstep may be initiated while the distributing step is being completed.This may reduce the overall cycle time of the additive manufacturingapparatus 100 to less than the sum of the distributing cycle time (alsoreferred to herein as the recoat cycle time), the depositing cycle time(also referred to herein as the print cycle time), and/or the cleaningcycle time.

While FIGS. 1 and 2 schematically depict an embodiment of an actuatorassembly 102 which comprises an upper support 182 and a lower support184 with the recoat head actuator 144 and the print head actuator 154mounted thereto, respectively, it should be understood that otherembodiments are contemplated and possible, such as embodiments whichcomprise more than two supports and more than two actuators. Moreover,it is contemplated that embodiments may include a single support havingthe recoat head actuator 144 and the print head actuator 154 mountedthereto.

Cleaning Station

Turning now to FIGS. 3A and 3B, an embodiment of the cleaning station110 is shown in greater detail. Although described in variousembodiments as being associated with the additive manufacturingapparatus 100 of FIGS. 1 and 2, it is contemplated that the cleaningstation 110 and fluid management system coupled thereto may be used withother types of additive manufacturing apparatuses known and used in theart.

The cleaning station 110 may comprise a cleaning station vessel 314positioned proximate at least one binder purge bin 302. As shown inFIGS. 3A and 3B, the cleaning station 110 is positioned between twobinder purge bins 302, each of which is configured to receive material,such as contaminants and binder material, discharged by the print head.Although shown in FIGS. 3A and 3B as including two binder purge bins302, it is contemplated that in embodiments, only one binder purge bin,or more than two binder purge bins, may be included. In embodiments, thebinder purge bin 302 optionally includes a purge wiper 303 (FIG. 3B)positioned between the binder purge bin 302 and the wet wipe cleanersection 304. When included, the purge wiper 303 can contact the printhead after contaminants and binder material are discharged into thebinder purge bin 302 to remove loose contaminants and binder materialfrom the face of the print head before the print head is introduced tothe wet wipe cleaner section 304. In embodiments, the purge wiper 303redirects the loose contaminants and binder material into the binderpurge bin 302 for disposal, thereby reducing the amount of contaminantsand binder material introduced into the cleaning station 110 during thecleaning process.

Further as shown, the cleaning station vessel 314 is a container whichincludes a wet wipe cleaner section 304, a dry wipe cleaner section 306,and a capping section 308. In various embodiments, the wet wipe cleanersection 304, the dry wipe cleaner section 306, and the capping section308 are sections of a cleaning station vessel 314 containing a volume ofcleaning fluid. The wet wipe cleaner section 304 applies cleaning fluidto the print head, specifically, a faceplate of the print head. The drywipe cleaner section 306, which in some embodiments is downstream of thewet wipe cleaner section 304, removes excess liquid (e.g., cleaningfluid and contaminants) from the print head in advance of binderjetting. The capping section 308, which may be also considered an idlesection, is a location where the print head may be temporarily placed inadvance of binder jetting. In embodiments, the capping section 308supplies cleaning fluid to the print head faceplate to prevent binderfrom drying on the print head. Without being limited to theory,maintaining the wet wipe cleaner section 304, the dry wipe cleanersection 306, and the capping section 308 within a single cleaningstation vessel 314 is highly advantageous as it streamlines cleaningfluid management by eliminating the need to control three separatecleaning station vessels. In this embodiment, cleaning fluid maintenanceis limited to a single cleaning station vessel 314.

In embodiments, the cleaning station vessel 314 includes at least onemoveable wall 316 extending vertically upward (e.g., +/−Z) from thecleaning station vessel 314 and in a direction parallel to a directionof movement of the print head 150 through the cleaning station 110(e.g., +/−X). When included, the moveable wall 316 redirects cleaningfluid into the cleaning station vessel 314. For example, cleaning fluidthat is splashed, such as from the movement of the wet wipe member 310and/or the dry wipe member 312 into and out of the cleaning stationvessel 314, may be redirected back into the cleaning station vessel 314rather than being lost into the environment (e.g., onto the floor). Inembodiments, the moveable wall 316 may be coupled to one or moreactuators to enable movement of the wall. For example, the moveable wall316 may be moved in the +Z direction when the print head 150 enters thecleaning station 110, and in the −Z direction when the print head 150leaves the cleaning station 110. Additionally or alternatively, themoveable wall 316 may be moved along the +/−X direction through thecleaning station 110 along a path parallel to the path of the print head150.

In embodiments, the moveable wall 316 is coupled to the wall of thecleaning station vessel 314 through a guide slot (not shown), and ismoveable within the guide slot. Accordingly, in the event that the printhead 150 or another item contacts the moveable wall 316, the moveablewall 316 will yield (e.g., move) rather than causing damage to the printhead 150 or other part of the additive manufacturing apparatus 100. Itis contemplated that the moveable wall 316 could be coupled to the wallof the cleaning station vessel 314 in other ways, including through theuse of magnetic mounts, bolts, or slotted holes, for example.

In embodiments, the cleaning station vessel 314 is in fluidcommunication with an overflow vessel 318, as shown in FIG. 3C, such asthrough a fluid level wall 320. Accordingly, the cleaning fluid may becontinuously pumped into the cleaning station vessel 314, as will bedescribed in greater detail below. When the cleaning fluid in thecleaning station vessel 314 reaches the top of the fluid level wall 320,the cleaning fluid flows over the fluid level wall 320 and into theoverflow vessel 318. In embodiments, the overflow vessel 318 includes atleast two fluid level sensors 322, each positioned at a differentvertical position within the overflow vessel 318. Accordingly, cleaningfluid is pumped into the cleaning station vessel 314, flows over thefluid level wall 320 and into the overflow vessel 318 until both of thefluid level sensors 322 detect cleaning fluid, indicating that the fluidlevel of the cleaning fluid within the overflow vessel 318 is at orabove the vertical position of the fluid level sensor 322 that is closerto the top of the overflow vessel 318. In response to both of the fluidlevel sensors 322 detecting the fluid, cleaning fluid is pumped out ofthe overflow vessel 318, such as through a drain 824 in the overflowvessel 318, until neither of the fluid level sensors 322 detects thefluid, indicating that the fluid level of the cleaning fluid within theoverflow vessel 318 is below the vertical position of the fluid levelsensor 322 that is closer to the bottom of the overflow vessel 318. Inembodiments, the fluid level wall 320 can be adjusted to control thevertical height of the top of the fluid level wall 320 and, accordingly,the fluid level within the cleaning station vessel 314.

Referring again to FIGS. 1, 2, 3A, and 3B, in the embodiments describedherein, the print head 150 may deposit the binder material 500 on alayer of build material 400 distributed on the build platform 120through an array of nozzles 172 located on the underside of the printhead 150 (i.e., the surface of the print head 150 facing the buildplatform 120). In one or more embodiments, the nozzles 172 may bepiezoelectric print nozzles and, as such, the print head 150 is a piezoprint head. In alternative embodiments, the nozzles 172 may be thermalprint nozzles and, as such, the print head 150 is a thermal print head.

In general, after the print head 150 has deposited the binder material500 on the layer of build material 400 positioned on the build platform120 (FIG. 1), it is moved to the binder purge bin 302, wherecontaminants are dislodged via backpressure and, in embodiments, usingbinder material 500 ejected from the nozzles 172. In embodimentsincluding a purge wiper 303 (FIG. 3B), the print head 150 is wiped bythe purge wiper 303 as it is moved from the binder purge bin 302 towardthe wet wipe cleaner section 304 to direct loose contaminants and bindermaterial from the face of the print head 150 into the binder purge bin302. Next, the print head 150 is moved to the wet wipe cleaner section304 where a cleaning fluid is applied to the print head 150 andcontaminants are mechanically removed from the print head 150. The printhead 150 is then moved to the dry wipe cleaner section 306 where thecleaning fluid and remaining contaminants are removed, before the printhead 150 is moved to the second binder purge bin 302. At the secondbinder purge bin 302, any remaining contaminants are dislodged and thebinder meniscus is reestablished by ejecting binder material 500 fromthe nozzles 172. In embodiments in which the print head 150 is idle,instead of moving to the second binder purge bin 302, the print head 150may be moved to the capping section 308 where it is kept moist toprevent the binder material from drying out and clogging the nozzles 172of the print head 150. Each of the sections of the cleaning station 110will now be described in greater detail.

Cleaning Station—Wet Wipe Cleaner Section

Various suitable embodiments are contemplated for the wet wipe cleanersection 304. As shown in FIGS. 3A and 3B, the wet wipe cleaner section304 comprises a wet wipe member 310. The wet wipe member 310 comprisesany suitable mechanism for passively applying cleaning fluid to a printhead, for example, a brush, a squeegee, and the like. As used herein,“passively applying” means the wet wipe member 310 contacts the printhead as it traverses the wet wipe cleaner section 304. The wet wipemember 310 is connected to one or more actuators 311 that raise or lowerthe wet wipe member within the wet wipe cleaner section 304 of thecleaning station vessel 314. The actuators may comprise linearactuators, rotary actuators, or electric actuators. While variousactuators and actuator locations are considered suitable, the actuators311 depicted in FIGS. 3A and 3B are disposed primarily outside thecleaning station vessel 314. Without being bound by theory, minimizingactuator 311 contact with the cleaning fluid, especially contact withany electronic components of the actuators 311, may be beneficial inmaintaining actuator performance. Thus, some embodiments will includethe actuators 311 primarily positioned outside the cleaning stationvessel 314.

Referring now to FIGS. 4A-4E, additional embodiments of the wet wipecleaner section 304 are schematically depicted. Specifically as shown inFIGS. 4A-4E, a wet wipe member 310 for applying cleaning fluid to theprint head 150 is depicted. The wet wipe member 310 includes a wet wiperbody 401 having a top side 402 and a bottom side 404. The wet wipemember 310 includes at least one wiper blade 406 vertically extendingfrom the top side 402 of the wet wiper body 401. In the embodiment shownin FIGS. 4A and 4B, the wet wipe member 310 includes a first wiper blade406 a and a second wiper blade 406 b (collectively, the wiper blades406), spaced apart from one another. In the embodiment shown in FIG. 4C,the wet wipe member 310 includes a single wiper blade 406. Accordingly,any number wiper blades may be included in the wet wipe member 310.

Although the wet wipe member 310 is described in various embodiments asincluding at least one wiper blade 406, in embodiments, the wet wipemember 310 does not include wiper blades, as shown in FIG. 4E.

A fluid channel 408 extends horizontally from a first end 410 of the wetwiper body 401 to a second end 412 of the wet wiper body 401, as shownin FIGS. 4A-4C, and defines a recessed path within the wet wiper body401. The fluid channel 408 has an open top to allow cleaning fluid toflow out of the fluid channel 408. The rate of the flow of the cleaningfluid through the fluid channel 408 is controlled in embodiments,thereby enabling control of the height of a fluid wall 418 created bythe cleaning fluid, shown in FIG. 4E. In embodiments, such as theembodiment shown in FIGS. 4A and 4B, the fluid channel 408 is positionedbetween the first wiper blade 406 a and the second wiper blade 406 b.Although the wiper blades 406 and the fluid channel 408 are describedherein as extending from a first end 410 to the second end 412 of thewet wiper body 401, in embodiments, the wet wiper body 401 has a lengthfrom the first end 410 to the second end 412 that is greater than alength of the wiper blades 406 and/or the fluid channel 408. Forexample, in embodiments, the wiper blades 406 and/or the fluid channel408 may be positioned within the wet wiper body 401 with the wet wiperbody 401 extending about 1 mm, about 2 mm, about 5 mm, or about 10 mm oneach end. This additional length of the wet wiper body 401 can enable,for example, the wet wiper body 401 to extend from end to end of thecleaning station while the wiper blades 406 and/or the fluid channel 408are sized to have substantially the same length as the print head.

As shown in FIG. 4E, in embodiments in which the wet wipe member 310does not include wiper blades 406, the flow of the cleaning fluidthrough the fluid channel 408 is controlled to provide a touchlesswiping system that uses the fluid wall 418 to wipe contaminants from theprint head without requiring the use of wiper blades. Moreover, inembodiments, a vacuum wipe member 420 (FIG. 4F) may be included. Thevacuum wipe member 420 may be similar in structure to the wet wipemember 310, including a channel 422 and optionally one or more wiperblades 406. However, the channel 422 in the vacuum wipe member 420enables process gasses (e.g., air, argon, nitrogen, or the like) to bedrawn through the channel, thereby generating a vacuum effective to pullliquids and contaminants off of the print head as it passes over thevacuum wipe member 420. When included, the vacuum wipe member 420 iscoupled to a pump (not shown) for generating the vacuum as well as atleast one filter (not shown) to prevent contaminants from being pulledinto the pump. In embodiments, the vacuum wipe member 420 can beincluded with a wet wipe member 310, such as the wet wipe member 310shown in any of FIGS. 4A-E, or can be independently included in thecleaning station 110.

In embodiments, each of the wiper blades 406 a has the same vertical(e.g., +/−Z) position as the other blades 406 b, as shown in FIG. 4A.Accordingly, all of the wiper blades 406 a, 406 b has the sameengagement distance with the print head 150 during wiping operations. Asis known in the art, the “engagement distance” refers to the amount bywhich the vertical position of the print head 150 and the verticalposition of an undeflected wiper blade 406 overlap. However, inembodiments, one or more wiper blades 406 a are positioned at a firstvertical position while one or more wiper blades 406 b are positioned ata second vertical position, as shown in FIG. 4G. In such embodiments, aleast one wiper blade 406 a has a different engagement distance than thewiper blades 406 b. For example, the wiper blades 406 may be positionedsuch that the engagement distance with the print head 150 increasesalong the path of the print head 150 during the wet wiping process.

As shown in FIGS. 4A-4C, the wet wipe member 310 further includes acleaning manifold 414 that extends below the fluid channel 408 withinthe wet wiper body 401. The cleaning manifold 414 is in fluidcommunication with the fluid channel 408 through at least one fluid port407 to provide cleaning fluid from the cleaning manifold 414 to the topside 402 of the wet wiper body 401, e.g., via the fluid channel 408. Inthe embodiment shown in FIG. 4B, twelve fluid ports 407 provide cleaningfluid from the cleaning manifold 414 to the fluid channel 408. Eachfluid port 407 may have a circular cross-section, a squarecross-section, or other cross-section suitable for fluid flow. However,in the embodiment shown in FIG. 4D, one fluid port 407 provides cleaningfluid from the cleaning manifold 414 to the fluid channel 408. The fluidport 407 in FIG. 4D extends from the first end 410 to the second end 412of the wet wiper body 401 and has a substantially rectangularcross-section. Other shapes, sizes, and quantities of fluid ports arepossible and contemplated. In embodiments, such as the embodiment shownin FIG. 4B where the fluid channel 408 is positioned between first andsecond wiper blades 406, the fluid port 407 is also disposed between thefirst and second wiper blades 406.

In various embodiments, the cleaning fluid is provided to the cleaningmanifold 414 through a plurality of cleaning fluid inlets 416 that arefluidly coupled to a cleaning fluid reservoir or cleaning fluidmanagement system, described in greater detail below. The plurality ofcleaning fluid inlets 416 may be, for example, fluid conduits thatextend vertically upward through the bottom side 404 of the wet wiperbody 401. However, in embodiments, the plurality of cleaning fluidinlets 416 additionally or alternatively extend from a side 403 of thewet wiper body 401 adjacent to the top side 402 and the bottom side 404of the wet wiper body 401. The plurality of cleaning fluid inlets 416are operable to receive the cleaning fluid and provide the cleaningfluid to the cleaning manifold 414. The cleaning fluid inlets 416 are influid communication with the fluid port 407 through the cleaningmanifold 414 such that cleaning fluid enters the cleaning manifold 414through the cleaning fluid inlets 416 and exits the cleaning manifold414 through the fluid port 407.

As stated above, the wet wipe member 310 is coupled to one or moreactuators 311 which are operable to raise or lower the wet wipe member310 into and out of the volume of the cleaning fluid. For example, thewet wipe member 310 may be actuated just prior to the print head 150moving to the wet wipe cleaner section 304 such that the wet wipe member310 is raised out of the volume of the cleaning fluid and contacts theprint head 150 as it is moved through the wet wipe cleaner section 304.In various embodiments, the wet wipe member 310 is actuated as close tothe time that it will make contact with the print head 150 as possible,so as to ensure that the wiper blades 406 are wet with cleaning fluid,although it is contemplated that some period of time may pass betweenthe wet wipe member 310 being raised out of the volume of the cleaningfluid and making contact with the print head 150.

As another example, the wet wipe member 310 may be actuated after theprint head 150 has moved to the dry wipe cleaner section 306 such thatthe wet wipe member is lowered into the volume of the cleaning fluid.The lowering of the wet wipe member into the cleaning fluid may washaway contaminants on the surface of the wiper blades 406 and clean thewet wipe member 310, thereby reducing the likelihood that the wet wipemember 310 will introduce contaminants to the print head 150. Additionaldetails on the actuation of wet wipe member 310 embodiments aredescribed below.

In various embodiments, the cleaning manifold 414 fills with thecleaning fluid and feeds the fluid channel 408, which fills from thebottom of the fluid channel 408. In embodiments in which the fluidchannel 408 is positioned between the wiper blades 406, the cleaningfluid forms a pool of cleaning fluid between the wiper blades 406. Inone or more embodiments, the cleaning fluid flows over the sides of thefluid channel 408 and into overflow drains, which return the cleaningfluid to the cleaning manifold 414. In further embodiments, the cleaningfluid is fed through the wet wipe member 310 continuously duringoperation of the additive manufacturing apparatus. After the wet wipemember applies liquid to the print head, the liquid then overflows backinto the cleaning station vessel 314. As described more below, withinthe cleaning station vessel 314, there is a drain 824 (see FIG. 3B),which directs cleaning fluid into a cleaning fluid reservoir 816 (seeFIG. 8), and is then pumped back into the wet wipe member 310. Thecontinuous cleaner circulation and recirculation is described morebelow.

Accordingly, when the wet wipe member 310 is actuated, cleaning fluid issupplied to the print head 150 to dissolve contaminants while the wiperblades 406 mechanically remove contaminants. While the cleaning fluidmay dissolve the contaminants in some cases, the contaminants may alsobe considered as mixed or suspended within the cleaning fluid. Thecleaning manifold 414 and the fluid channel 408 ensure that cleaningfluid can be directly applied to the print head 150 during cleaningwhile compensating for any delay that may result from the use of pumpsin the fluid management system, as will be discussed in greater detailbelow. In particular, the cleaning manifold 414 and the fluid channel408 provide a local reservoir of cleaning fluid that can be used evenwhen the pumps are not actively providing cleaning fluid to the wet wipemember 310.

In the embodiment depicted in FIG. 4A, the cleaning fluid does not flowto the top of the wiper blades 406. However, it is contemplated that inother embodiments, a pair of walls extends between the first wiper blade406 a and the second wiper blade 406 b from the top side 402 of the wetwiper body 401 to a top of each of the first wiper blade 406 a and thesecond wiper blade 406 b. The pair of walls thus extends the depth ofthe fluid channel 408 to the top of the wiper blades 406, enabling thecleaning fluid to fill up to the top of the wiper blades 406. Suchembodiments may enable greater dissolution of contaminants on the printhead 150, and may facilitate the wiping by further wetting both thewiper blades 406 and the print head 150.

Cleaning Station—Dry Wipe Cleaner Section

Similar to the wet wipe cleaner section 304, various suitableembodiments are contemplated for the dry wipe cleaner section 306.Referring to the embodiments depicted in FIGS. 3A-3B, the dry wipecleaner section 306 comprises a dry wipe member 312. The dry wipe member312 comprises any suitable mechanism (e.g., brush, a squeegee, and thelike) for removing cleaning fluid and contaminants. For example, the drywipe member 312 may remove cleaning fluid and contaminants from theprint head 150. Like the wet wipe member 310, the dry wipe member 312 iscoupled to one or more actuators 313 that raise or lower the dry wipemember 312 within the dry wipe cleaner section 306 of the cleaningstation vessel 314. While various actuators and actuator locations areconsidered suitable, the actuators 313 depicted in FIGS. 3A-3B aredisposed primarily outside the cleaning station vessel 314. Withoutbeing bound by theory, minimizing actuator 313 contact with the cleaningfluid, especially contact with any electronic components of theactuators 313, may be beneficial in maintaining actuator performance.Thus, some embodiments will include the actuators 313 primarilypositioned outside the cleaning station vessel 314. The actuators 313can be linear actuators, rotary actuators, pneumatic actuators, orelectric actuators. Additional details on the actuators 313 is providedhereinbelow.

An embodiment of the dry wipe member 312 is depicted in FIG. 5A. The drywipe member 312 may define a wiper array, which includes a wipermounting member 501 and a plurality of dry wiper blades 502 mounted tothe wiper mounting member 501. Each of the plurality of dry wiper blades502 may include a body member 514 and a blade 516 extending from thebody member 514. The wiper mounting member 501 extends along alongitudinal axis LA, and a length l of each of the plurality of drywiper blades 502 extends in a direction that is at an angle θ that isgreater than 0 and less than 90° relative to the longitudinal axis LA.In some embodiments, each of the plurality of dry wiper blades 502extends in a direction that is at an angle θ of from 5° to 50°, 5° to45°, or from 10° to 30° relative to the longitudinal axis LA. The angleθ may be varied to provide for additional contact with the print head150, as may be desired in embodiments.

As described above, each of the plurality of dry wiper blades 502 has anoverlap of at least part of its length l with the length l of anadjacent dry wiper blade 502 in a direction orthogonal to thelongitudinal axis LA. In embodiments, each of the plurality of dry wiperblades 502 has an overlap of at least 30% of its length l with thelength of an adjacent dry wiper blade in a direction orthogonal to thelongitudinal axis LA. For example, in some embodiments, each of theplurality of dry wiper blades 502 may have an overlap of from 30% to 70%of its length with the length of an adjacent dry wiper blade in adirection orthogonal to the longitudinal axis LA. Such an arrangementenables the dry wipe member 312 to contact the print head 150 with atleast two blades 516 over the entire length of the print head 150. Otherarrangements are contemplated, such as arrangements that enable the drywipe member 312 to contact the print head 150 with three or more blades516 over the entire length of the print head 150. Without being bound bytheory, it is believed that because the dry wiper blades are angled withrespect to the longitudinal axis LA and their lengths overlap withadjacent dry wiper blades, the dry wipe member 312 imparts less drag onthe print head 150 as it wipes cleaning fluid from the print head 150and is thereby more effective in wiping off the cleaning fluid.Additionally, the use of the array of angled dry wiper blades may resultin the cleaning fluid being drained away from the print head 150 in lesstime compared to a single wiper blade extending along the longitudinalaxis LA.

In embodiments, each of the blades 516 has the same vertical (e.g.,+/−Z) position as the other blades 516. Accordingly, all of the blades516 has the same engagement distance with the print head 150 duringwiping operations. As is known in the art, the “engagement distance”refers to the amount by which the vertical position of the print head150 and the vertical position of an undeflected blade 516 overlap.However, as shown in FIG. 5D, in embodiments, one or more blades 516 arepositioned at a first vertical position Z₁ while one or more blades 516are positioned at a second vertical position Z₂. In such embodiments, aleast one blade 516 has a different engagement distance than the blades516. For example, the blade 516 positioned at the first verticalposition Z₁ has a smaller engagement distance than the blade 516positioned at the second vertical position Z₂. In embodiments, theblades 516 may be positioned such that the engagement distance with theprint head 150 increases along the path of the print head 150 during thedry wiping process. Such embodiments can, for example, reduce the amountof cleaning fluid that is expelled from the cleaning station 110 duringthe cleaning process.

In some embodiments, the wiper mounting member 501 includes channels504, as shown in FIG. 5B. Each channel 504 is formed in a top face 506of the wiper mounting member 501 and is shaped to receive one of theplurality of dry wiper blades 502. The formation of the channels 504 toreceive the plurality of dry wiper blades 502 may enable the pluralityof dry wiper blades 502 to be securely and accurately coupled to thewiper mounting member, which may ease manufacturing of the dry wipemember 312 and prevent movement of the dry wiper blades 502 with respectto the wiper mounting member 501 during use.

As depicted in FIG. 5B, in embodiments, each channel may include a hole508 extending through the thickness of the wiper mounting member 501. Inembodiments in which the wiper mounting member 501 does not includechannels, a plurality of holes 508 may be positioned along the length ofthe wiper mounting member 501, with each of the plurality of holes 508extending through the thickness from the top face 506 to a bottom face510 of the wiper mounting member 501, as shown in FIG. 5C. In variousembodiments, an attachment member 512, such as a screw, bolt, or otherattachment mechanism, may be coupled to the body member 514 of each ofthe plurality of dry wiper blades 502 through the hole 508. Although invarious embodiments, the plurality of dry wiper blades 502 are coupledto the wiper mounting member 501 by coupling an attachment member 512 tothe body member 514, other methods of mounting the plurality of drywiper blades 502 to the wiper mounting member 501 are possible andcontemplated. For example, each of the plurality of dry wiper blades 502can be secured within the wiper mounting member 501 using end caps thatare bolted in place. While the above wiper array of FIGS. 5A-5D isdiscussed for use as a dry wipe member 312, it is further contemplatedthat the wiper array could also be included as a wet wipe member 310 ora purge wiper 303 (FIG. 3B).

In further embodiments, the dry wipe member 312 is coupled to twoactuators (e.g., actuators 313) which are operable to raise or lower thedry wipe member 312 into and out of the volume of the cleaning fluid.For example, the dry wipe member 312 may be actuated such that the drywipe member 312 is raised out of the volume of the cleaning fluid withsufficient time to allow the cleaning fluid to drain away from the drywiper blades 502. The dry wipe member 312 contacts the print head 150 asit is moved through the dry wipe cleaner section 306 to remove cleaningfluid, contaminants and other debris from the print head 150 after theprint head 150 is cleaned by the wet wipe member 310.

As another example, the dry wipe member 312 may be actuated after theprint head 150 has moved to the capping section 308 or the buildplatform 120 such that the dry wipe member 312 is lowered into thevolume of the cleaning fluid. The lowering of the dry wipe member 312into the cleaning fluid may wash away contaminants on the surface of thedry wiper blades 502 and clean the dry wipe member 312, thereby reducingthe likelihood that the dry wipe member 312 will introduce (orreintroduce) contaminants to the print head 150. In some embodiments,the dry wipe member 312 is lowered into the volume of the cleaning fluidfor a period of time sufficient to rinse the dry wipe member 312, andthen is raised out of the volume of the cleaning fluid until it has beenused to wipe the print head 150 again.

Cleaning Station—Capping Section

As described with reference to FIGS. 3A-3C, in various embodiments, thecleaning station 110 includes a capping section 308 including a cover701 to create or maintain a non-curing environment around the print head150. As used herein, a “non-curing environment” means an environment inwhich the binder material does not cure within or on the surface of thenozzles of the print head 150. The non-curing environment may bemaintained, for example, by maintaining a particular humidity level,temperature, or the like, that prevents the binder material from curing.Various suitable embodiments are contemplated.

An example embodiment of a capping section 308 is shown in greaterdetail in FIG. 7A. In particular, the capping section 308 includes acover 701 in the form of a sponge 702 supported by a sponge support 704coupled to an actuator 706 operable to raise and lower the sponge 702into and out of the cleaning fluid within the cleaning station 110.Accordingly, the sponge 702 may be used to soak up cleaning fluid fromthe cleaning station 110 and the sponge 702 may be applied to the printhead 150 while the print head 150 is idle. Without being bound bytheory, the application of the wet sponge 702 to the print head 150 mayreduce evaporation of binder material in one or more jet nozzles of theprint head 150 and/or prevent the curing thereof. In other words, whenthe print head 150 is in an idle state, the print head 150 may belocated at the capping section 308 to maintain the print head 150 in anon-curing environment, which, in embodiments, includes maintaining theprint head 150 in a humid, moist, wet, or submerged state.

The sponge 702 can be formed of any suitable material capable ofabsorbing and holding the cleaning fluid for a predetermined period oftime. In some embodiments, the sponge 702 may be made from cellulosewood fibers or foamed plastic polymers. In some particular embodiments,the sponge 702 may be made from a silicone material, such as a foamedsilicone, a polyurethane, a polyimide, or combinations thereof.

The sponge support 704 can be a metal or plastic plate sized to supportthe sponge 702. In some embodiments, the sponge 702 may be coupled tothe sponge support 704, such as through the use of an adhesive layerbetween the sponge 702 and the sponge support 704, or an attachmentmember, such as a bolt, screw, or other mechanism to attach the sponge702 to the sponge support 704. In some embodiments, the sponge 702 maybe removably coupled to the sponge support 704 such that the sponge 702can be easily replaced without also replacing the sponge support 704 andactuator 706.

As shown in FIG. 7A, in some embodiments, the sponge support 704 mayinclude edges 704 a that extend in an upward direction from a base 704b. However, it is contemplated that in other embodiments, the spongesupport 704 includes only the base 704 b, and does not include raisededges 704 a. In embodiments, the sponge support 704 may be perforated orotherwise include one or more holes through the thickness of the spongesupport 704 to enable cleaning fluid in the cleaning station to beabsorbed by the sponge 702. In other embodiments, the sponge 702 andsponge support 704 may be positioned such that the fluid level 600 ofthe cleaning fluid is above the edges 704 a (if any) of the spongesupport 704 such that the cleaning fluid is in contact with the sponge702.

The sponge support 704 is coupled to an actuator 706 that is operable toraise and lower the sponge 702 within the cleaning fluid. The actuator706 may be a linear actuator, a rotary actuator, a pneumatic actuator,an electric actuator, or any other suitable type of actuator selectedbased on the particular embodiment. Although depicted in FIG. 7A asbeing coupled to the sponge 702 through the sponge support 704, it iscontemplated that in some embodiments, the actuator 706 may be directlycoupled to the sponge 702, and a sponge support 704 may not be included.Such embodiments, for example, may be employed when the sponge 702 ismade from a stiff, yet absorbent, material.

In the embodiment shown in FIG. 7A, the actuator 706 is coupled to apassive resistance mechanism 708, which biases the sponge 702 toward araised position such that at least a portion of the sponge 702 is abovethe fluid level 600 of the cleaning fluid and able to contact the printhead 150. The passive resistance mechanism 708 may be, by way of exampleand not limitation, a spring biased in an upward direction. Theincorporation of a passive resistance mechanism 708, though optional,serves as a fail-safe to ensure that, in the event of an actuatorfailure, the sponge 702 is positioned for use to maintain the print head150 in a non-curing environment. Additionally or alternatively, theincorporation of the passive resistance mechanism 708 may enable energysavings by enabling power to the actuator 706 to be reduced or turnedoff while the print head 150 is idle without causing the sponge 702 tobe retracted below the fluid level of the cleaning fluid.

In various embodiments, when the print head 150 is located at thecapping section 308 of the cleaning station 110, the sponge 702 is atleast partially submerged in the cleaning fluid. In other words, some orall of the sponge 702 extends below the fluid level 600 of the cleaningfluid to enable the sponge 702 to be constantly absorbing cleaning fluidfrom the cleaning station 110. In some such embodiments, at least aportion of the sponge 702 extends above the fluid level 600 of thecleaning fluid such that the sponge 702 is in contact with the printhead 150 without submerging the print head 150 in the cleaning fluid. Inembodiments, 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%,or even 99% of the volume of the sponge 702 may extend above the fluidlevel 600 of the cleaning fluid.

In practice, to clean the print head 150, cleaning fluid is applied tothe print head 150 using the wet wipe member 310 by passing the printhead 150 through the wet wipe cleaner section 304. Then, cleaning fluidis removed from the print head 150 using the dry wipe member 312 bypassing the print head 150 through the dry wipe cleaner section 306.Then, when the print head 150 will be idle or the additive manufacturingapparatus 100 is undergoing maintenance, the print head 150 is moved tothe capping section 308 and into contact with the sponge 702 that is atleast partially submerged in the cleaning fluid. In other embodiments(not shown), it is not required for the sponge to be submerged in thecleaning fluid. The sponge 702 is maintained in contact with the printhead 150 while the print head 150 is idle or the additive manufacturingapparatus 100 is undergoing maintenance, thereby reducing evaporation ofbinder material in the nozzles of the print head 150, preventing thecuring of the binder material around the print head 150, and the like.

Although described above as including a sponge 702, in some embodiments,the cover 701 of the capping section 308 is a cap 710, as shown in FIG.7B. In embodiments, the cap 710 may be sealed around the print head 150when the print head 150 is idle to prevent the evaporation of bindermaterial from the nozzles of the print head 150, to maintain a humiditylevel around the print head 150, and/or to maintain or create anon-curing environment around the print head 150. As shown in FIG. 7B,in embodiments, the cap 710 may include a volume of cleaning fluid,thereby forming a smaller cleaning vessel within the cleaning stationvessel 314, so as to create a humid, non-curing environment around thenozzles of the print head 150, although in some embodiments, the cap 710may not include a volume of fluids.

As with the sponge 702, the cap 710 is coupled to an actuator 706 thatis operable to raise and lower the cap 710 within the cleaning fluid.The actuator 706 may be a linear actuator, a rotary actuator, apneumatic actuator, an electric actuator, or any other suitable type ofactuator selected based on the particular embodiment. In the embodimentshown in FIG. 7B, the actuator 706 is coupled to a passive resistancemechanism 708, which biases the cap 710 toward a raised position suchthat at least a portion of the cap 710 is above the fluid level 600 ofthe cleaning fluid and able to contact the print head 150. The passiveresistance mechanism 708 may be, by way of example and not limitation, aspring biased in an upward direction. The incorporation of a passiveresistance mechanism 708, though optional, serves as a fail-safe toensure that, in the event of an actuator failure, the cap 710 ispositioned for use to maintain the print head 150 in a non-curingenvironment. Additionally or alternatively, the incorporation of thepassive resistance mechanism 708 may enable energy savings by enablingpower to the actuator 706 to be reduced or turned off while the printhead 150 is idle without causing the cap 710 to be retracted below thefluid level of the cleaning fluid.

In embodiments, the actuator 706 enables the height of the cap 710 to beadjusted relative to the print head 150. Accordingly, the cap 710 may bepositioned to contact the print head 150 with fluid contained within thecap 710, or the cap 710 may be positioned to cap the print head 150 suchthat the face of the print head 150 is not contacted by the fluid.

In embodiments, the cap 710 may further include one or more gaskets orseals 712 to create a seal between the cap 710 and the print head 150when the cap 710 is in use. The creation of a seal may minimize or eveneliminate evaporation of the cleaning fluid in the cap 710, the bindermaterial in the print head 150, or both. Moreover, in embodiments, thecap 710 may include one or more ports 714 (e.g., inlet and outlet ports)to enable cleaning fluid to be flowed through the cap 710 during use.Accordingly, the cleaning fluid in the cap 710 can be replenished orrefreshed.

In still other embodiments, the cap 710 of FIG. 7B may be combined withthe capping section 308 shown and described with respect to FIG. 7A,such that the sponge 702 may be actuated into and out of the cap 710,which seals around the print head 150. In such embodiments, the cap 710may be selectively sealed around the print head 150 and may be actuatedindependent of the sponge 702. For example, the sponge may be actuatedsuch that it is in contact with the print head 150 during relativelyshort periods of idleness, while the sponge may be retracted and the capmay be actuated and sealed around the print head 150 during longerperiods of idleness, such as when the additive manufacturing apparatus100 is powered off or undergoing maintenance.

In embodiments, as an alternative to a dedicated capping section 308,the cleaning station vessel 314 itself may form a cover for the printhead. In such embodiments, the cleaning station vessel 314 is coupled toone or more actuators 706 to move the cleaning station vessel 314 in avertical direction with respect to the print head 150, as shown in FIG.7C. Accordingly, the cleaning station vessel 314 can serve as a cappingsection 308 in such embodiments, and the print head 150 is capped by theentire cleaning station vessel 314. In embodiments, the cleaning stationvessel 314 may be equipped with seals 712 that may be actuated, eitherindependently (FIG. 7D) or with the cleaning station vessel 314 (FIG.7C) to create a seal between the cleaning station vessel 314 and theprint head 150. In addition to, or as an alternative to, actuation ofthe seals 712, it is contemplated that the seals 712 around theperimeter of the cleaning station vessel 314 may be inflatable sealsthat are inflated to provide a seal between the cleaning station vesseland the print head 150, as shown in FIGS. 7E and 7F.

It is further contemplated that, in embodiments, the print head 150 isactuatable in the vertical direction for sealing with the cleaningstation vessel 314. Accordingly, depending on the particular embodiment,one or more of the cleaning station vessel 314, seals positioned aroundthe perimeter of the cleaning station vessel 314, and the print head 150are moved in a vertical direction to enable a seal to be formed betweenthe cleaning station vessel 314 and the print head 150. As with thepreviously-described embodiments of the capping section 308, inembodiments, vertical movement of one or more of the cleaning stationvessel 314, seals positioned around the perimeter of the cleaningstation vessel 314, and the print head 150 is effective to maintain theprint head 150 in a non-curing environment.

Cleaning Station—Motion of Components

As has been described herein, various components of the cleaning station110, including the wet wipe member 310, the dry wipe member 312, and thecapping section 308, are configured to move in a vertical (e.g., +/−Z)direction during the cleaning of the print head 150. Although describedherein with reference only to the vertical component of the movement, itis contemplated that, in embodiments, the motion of the variouscomponents may have motion in other directions in addition to thevertical direction. For example, the motion may be in the form of an arcthat includes both horizontal and vertical motion.

In general, the various components of the cleaning station 110 eachindependently moves between an extended position, in which the componentis positioned to engage with or clean the print head 150, and aretracted position, in which the component is submerged within thecleaning fluid within the cleaning station vessel 314. For example, inembodiments, and with reference to FIGS. 3A and 3B, the print head 150enters the cleaning station 110 from the right hand side of the figure,passing over the second binder purge bin 302 first. In embodiments, asthe print head 150 proceeds from right to left, the capping section 308,the wet wipe member 310, and the dry wipe member 312 are in theretracted position such that they do not contact or clean the print head150. The print head 150 arrives at the first binder purge bin 302, wherebackpressure is applied to the print head 150 to discharge contaminantsfrom the print head 150 into the first binder purge bin 302. Inembodiments, during an additive manufacturing process, the print head150 discharges contaminants into the first binder purge bin 302 whilethe recoat head 140 is moving in the −X direction (e.g., a forwarddirection) in FIG. 1, supplying build material to a working surface ofthe build platform 120. The print head 150 then moves to the right,where the print head 150 is introduced to the wet wipe member 310. Thewet wipe member 310 is in an extended position to apply cleaning fluidto the print head 150. Next, the print head 150 is introduced to the drywipe member 312, which has moved to an extended position to wipe excesscleaning fluid from the print head 150, as described herein. Inembodiments, the wet wipe member 310 and/or the dry wipe member 312 arevertically raised out of the cleaning fluid before the completion of thedischarge of the contaminants from the print head 150 over the firstbinder purge bin 302. The wet wipe member 310 and/or the dry wipe member312 are retracted into the cleaning fluid in the cleaning station vessel314 after the print head 150 proceeds past them. For example, the wetwipe member 310 may be submerged in the cleaning fluid while the printhead 150 is being wiped by the dry wipe member 312. In embodiments,during an additive manufacturing process, the wet wiping and dry wipingsteps performed by the wet wipe member 310 and the dry wipe member 312,respectively, are performed while the recoat head 140 is moving in the+X direction (e.g., a reverse direction) from the build platform 120toward a recoat home position 148.

After being wiped, the print head 150 may be capped in the cappingsection 308, or it may proceed to the second binder purge bin 302, whereit is prepared for printing. For example, back pressure may be appliedto the print head 150 to equilibrate the print head 150 for printing. Inembodiments, the print head 150 then returns to the build platform 120to deposit binder material onto the powder layer, as described withrespect to FIG. 1.

Alternative orders in the operations of the components of the cleaningstation 110 are contemplated. For example, in embodiments, the printhead 150 enters the cleaning station 110 from the right hand side of thefigure, passing over the second binder purge bin 302 first. However, asthe print head 150 proceeds from right to left, the wet wipe member 310,the dry wipe member 312, or the wet wipe member 310 and the dry wipemember 312 are in the extended position such that they contact the printhead 150 along its path to the first binder purge bin 302. In suchembodiments, this can be a pre-cleaning step to remove surfacecontaminants prior to the discharging of additional contaminants overthe first binder purge bin 302.

In some embodiments, the wet wipe member 310 and/or the dry wipe member312 may be actuated using a two-stage actuation process to raise andlower the members out of and into the volume of cleaning fluid. Withoutbeing bound by theory, the two stage actuation improves cleaning fluiddraining from one or both of the dry and wet wipe members, because thecleaning fluid easily flows back into the cleaning station vessel 314when only one side of the wipe member is raised above the cleaning fluidlevel in stage one of the two stage actuation process. Because the drywipe member 312 is directed to removing cleaning fluid, not applying it,ensuring the cleaning fluid is quickly drained from the dry wipe member312 in the two-stage actuation process is desirable. However, inembodiments, other actuation processes, including single-stage actuationprocesses, are contemplated and possible.

The embodiment shown in FIGS. 6A-6C schematically depict a two-stageactuation process for raising the dry wipe members 312 out of thecleaning fluid of the cleaning station vessel 314. As shown in FIG. 6A,the dry wipe member 312 may be submerged in the cleaning station vessel314 of the cleaning station 110 such that the dry wipe member 312 isbelow a fluid level 600 of the cleaning fluid within the cleaningstation 110. Each of the wet wipe member 310 and the dry wipe member 312are coupled to a first actuator 602 a and a second actuator 602 b,respectively, for raising and lowering the members. Actuators 602 a, 602b in embodiments, may correspond to actuators 311 and 313 described inaccordance with FIGS. 3A and 3B. The first actuator 602 a is coupledproximate a first end of the wet wipe member 310 or the dry wipe member312 and the second actuator 602 b is coupled proximate a second end ofthe wet wipe member 310 or the dry wipe member 312. By “coupledproximate,” it is meant that the actuator is coupled at or near therespective end of the member. In embodiments, the first actuator 602 ais coupled to the wet wipe member 310 or the dry wipe member 312 at apoint that is closer to the first end than the second end of thecorresponding member, and the second actuator 602 b is coupled to thewet wipe member 310 or the dry wipe member 312 at a point that is closerto the second end than the first end of the corresponding member. Eachof the actuators 602 a and 602 b are independently operable to raise orlower the corresponding end of the dry wipe member 312 to which they arecoupled into and out of the volume of the cleaning fluid.

In FIG. 6A, dry wipe member 312 is not shown, as it is positionedbehind, and obscured by, the wet wipe member 310 in this view. As shownin FIG. 6B, the first actuator 602 a coupled to the dry wipe member 312is actuated to raise a first end 604 of the dry wipe member 312 abovethe fluid level 600 of the cleaning fluid while a second end 606 of thedry wipe member 312 remains below the fluid level 600. Although depictedin FIG. 6B as raising the first end 604 of the dry wipe member 312 tocompletely remove the first end 604 from the volume of cleaning fluid,it is contemplated that in some embodiments, the dry wipe member 312 maybe raised such that the dry wiper blades 502 (not shown in FIGS. 6A-6C)are above the fluid level while at least a portion of the wiper mountingmember 501 remains submerged in the cleaning fluid, below the fluidlevel 600. After the first end 604 of the dry wipe member 312 is raised,the second actuator 602 b coupled to the dry wipe member 312 is actuatedto raise the second end 606 of the dry wipe member 312 above the fluidlevel 600 of the cleaning fluid, as shown in FIG. 6C. As would beunderstood, lowering the dry wipe member 312 into the cleaning fluid maybe achieved by reversing the process described above and depicted inFIGS. 6A-6C. In embodiments, actuators 602 a and 602 b may be actuatedsimultaneously to lower the first end 604 and the second end 606 of thedry wipe member 312 at the same time, or during overlapping timeperiods.

Similarly, the embodiment shown in FIGS. 6D and 6E schematically depicta two-stage actuation process for raising the wet wipe member 310 out ofthe cleaning fluid of the cleaning station vessel 314. In particular, asshown in FIG. 6D, the first actuator 602 a coupled to the wet wipemember 310 is actuated to raise the first end 410 of the wet wipe member310 above the fluid level 600 of the cleaning fluid while the second end412 of the wet wipe member 310 remains below the fluid level 600.Although depicted in FIG. 6D as raising the first end 410 of the wetwipe member 310 to completely remove the first end 410 from the volumeof cleaning fluid, it is contemplated that in some embodiments, the wetwipe member 310 may be raised such that the wiper blades 406 are abovethe fluid level while at least a portion of the wet wiper body 401remains submerged in the cleaning fluid, below the fluid level 600.After the first end 410 of the wet wipe member 310 is raised, the secondactuator 602 b coupled to the wet wipe member 310 is actuated to raisethe second end 412 of the wet wipe member 310 above the fluid level 600of the cleaning fluid, as shown in FIG. 6E. As above, the wet wipemember 310 can be resubmerged in the cleaning fluid by reversing theprocess, actuating the second actuator 602 b and then actuating thefirst actuator 602 a of the wet wipe member 310. Alternatively, inembodiments, actuators 602 a and 602 b may be actuated simultaneously tolower the first end 410 and the second end 412 of the wet wipe member310 at the same time, or during overlapping time periods.

In some embodiments, the two-stage actuation process may occur for boththe dry wipe members 312 and the wet wipe members 310. This embodiment,which is sequentially illustrated in FIGS. 6A-6E, may be completedbefore or while the print head 150 is moved to the binder purge bin 302.After the print head 150 is moved passed the wet wipe cleaner section304 and the dry wipe cleaner section 306, the wet wipe member 310 andthe dry wipe member 312 may be returned to the cleaning fluid. Inparticular, after the print head 150 is passed over the wet wipe member310 and the dry wipe member 312, the actuators 602 a-602 b may beactuated to lower the wet wipe member 310 and the dry wipe member 312below the fluid level 600 of the cleaning fluid. In some embodiments,two or more of the actuators may be actuated simultaneously to lower thewet wipe member 310 and the dry wipe member 312 into the cleaning fluid,while in other embodiments, each of the actuators is independentlyactuated.

For example, in embodiments, the actuator 602 b is actuated while thefirst actuator 602 a is actuated to lower the first and second ends ofthe wet wipe member 310 or the dry wipe member 312 at substantially thesame time or during an overlapping time period. In embodiments, such asthe embodiment shown in FIGS. 6D and 6E, the actuator 602 a is actuatedto lower the first end 410 of the wet wipe member 310 into the volume ofcleaning fluid, then the actuator 602 b is actuated to lower the secondend 412 of the wet wipe member 310 into the cleaning fluid. Then, asshown in FIGS. 6A-6C, the actuator 602 a is actuated to lower the secondend 606 of the dry wipe member 312 into the volume of cleaning fluid,and finally, the actuator 602 b is actuated to lower the first end 604of the dry wipe member 312 into the cleaning fluid. Alternatively, asshown in to FIGS. 6D and 6E, the actuator 602 a is actuated to lower thefirst end 410 of the wet wipe member 310 into the volume of cleaningfluid, then the actuator 602 b is actuated to lower the second end 412of the wet wipe member 310 into the cleaning fluid. As shown in FIGS.6A-6C, then the actuator 602 a is actuated to lower the first end 604 ofthe dry wipe member 312 into the volume of cleaning fluid, and finally,the actuator 602 b is actuated to lower the second end 606 of the drywipe member 312 into the cleaning fluid. In still other embodiments, theorder of the lowering of the first end 410 and the second end 412 of thewet wipe member 310 is reversed, and in still other embodiments, the drywipe member 312 is lowered into the cleaning fluid before the wet wipemember 310 is lowered into the cleaning fluid. In embodiments, some orall of the actuators may be actuated simultaneously.

In embodiments, the first and second actuators 602 a, 602 b (and,accordingly, actuators 311 and 313) are electric actuators that areindependently operable to raise or lower the corresponding end of thewipe member (e.g., wet wipe member 310 or dry wipe member 312) at aplurality of speeds. Accordingly, in embodiments, the first actuator 602a is actuated to raise a first end of the wipe member at a first speedr₁, the second actuator 602 b is actuated to raise a second end of thewipe member at a second speed r₂, the second actuator 602 b is actuatedto lower the second end of the wipe member at a third speed r₃, and thefirst actuator 602 a is actuated to lower the first end of the wipemember at a fourth speed r₄, with at least one of the speeds differingfrom at least one of the other speeds. For example, the wet wipe member310 or the dry wipe member 312 may be raised at one speed and lowered atanother speed (e.g., r₁=r₂, r₃=r₄, r₄≠r₃), the first side may beactuated at one speed and the second side may be actuated at anotherspeed (e.g., r₁=r₄, r₂=r₃, r₄≠r₃), each actuation may be at a differentspeed from each other actuation (e.g., r₁≠r₂≠r₃≠r₄), or the like. Suchactuation can enable, for example, the wet wipe member 310 to emergefrom the cleaning fluid quickly to project cleaning fluid toward theprint head and to be submerged in the cleaning fluid to reduce orprevent splashing.

Although the wet wipe member 310 and the dry wipe member 312 aredescribed herein as being coupled to two actuators, it is contemplatedthat in other embodiments, each wipe member may be coupled to a singleactuator, or to more than two actuators. Moreover, although theactuators are described herein as being operable to raise and lower thecorresponding wipe member, it is contemplated that the actuators may beused in embodiments to cause additional movement of the wipe member. Forexample, in embodiments in which the actuators are electric actuators,the actuators may be actuated to cause agitation of the wipe memberwithin the cleaning station vessel 314, to adjust the position of thewipe member within the cleaning station vessel 314 or with respect tothe print head 150, or the like. Electric actuators may further enable“just in time” positioning of the wipe member and/or automaticcalibration routines. Other features and advantages are possible,depending on the particular embodiment. Commercially available electricactuators suitable for use include, by way of example and notlimitation, ERD electric cylinders available from Tolomatic, Inc.(Hamel, Minn.).

Although it is contemplated in embodiments that the actuators arecontrolled using a controller, such as control system 1000, inembodiments, one or more additional mechanisms may be included tomonitor, set, or limit the motion of the various components of thecleaning station 110. Such mechanisms may be desired, for example, toensure that the print head 150 is not damaged by the components of thecleaning station 110, while enabling the components to contact the printhead 150 as may be necessary to clean the print head 150. Accordingly,in embodiments, an adjustable hard stop 614 (FIG. 6F) may be present tolimit the vertical movement of one or more of the components within thecleaning station vessel 314.

In embodiments, a member 610 is coupled to an actuator 602 through amotion coupler 608 to provide or control of the upper position of themember 610 within the cleaning station 110, and specifically, thecleaning station vessel 314, as shown in FIG. 6F. The member 610 can be,for example, the wet wipe member 310, the dry wipe member 312, and/orthe cover of the capping section 308 (described in greater detailbelow), and the actuator 602 can be, for example, the one or morecorresponding actuators (e.g., actuators 311, 313, and 706,respectively). The at least one motion coupler 608 extends from themember 610 and is configured to couple the member 610 to the cleaningstation vessel 314 for vertical motion (e.g., along the +/−Z axis shownin the FIGS.) therein. In embodiments, the motion coupler 608 may bemade from metal coated with polytetrafluoroethylene (e.g., TEFLON™) orother suitable materials.

In the embodiment shown in FIG. 6F, the member 610 moves up and downwithin the cleaning station vessel 314 on a rail 612 through the motioncoupler 608. The rail 612 is coupled to an adjustable hard stop 614. Theadjustable hard stop 614 includes a threaded portion through which theadjustable hard stop 614 is coupled with a controlling bolt 616. Thecontrolling bolt 616 is additionally coupled with a rail cap 618 that isfixedly mounted on the rail 612. For example, the rail cap 618 mayinclude a clearance hole through which the controlling bolt 616 passesbefore it is coupled with the adjustable hard stop 614 through thethreaded portion of the adjustable hard stop 614. A nut 620 may be usedto prevent the controlling bolt 616 from moving upward. To adjust theadjustable hard stop 614, the controlling bolt 616 is tightened (to movethe adjustable hard stop 614 in the upward direction) or loosened (tomove the adjustable hard stop 614 in the downward direction).Accordingly, the position of the adjustable hard stop 614 is set to thedesired maximum height for the member 610. When the member 610 reachesto the desired maximum height, the adjustable hard stop 614 prevents themotion coupler 608 from continuing in the upward direction on the rail612.

Although only one end of the member 610 is shown in FIG. 6F, it iscontemplated in such embodiments, the member 610 includes a motioncoupler 608 on each end and, accordingly, each end of the member 610 maybe controlled in this fashion. In embodiments, a gauge or other indicia(not shown) may be included (e.g., machined into the rail 612 orcleaning station vessel 314) to enable the position of each end of themember 610 to be set at an equivalent position. Such indicia mayadditionally enable multiple members 610 to be set at a common desiredposition relatively easily.

In addition to, or as an alternative to, the hard stop, in embodiments agauge 1100 on the underside of the print head 150 is used to verticallyalign one or more of the components of the cleaning station 110, asshown in FIG. 11. In FIG. 11, the gauge 1100 is affixed to the bottomface 1102 of the print head 150, such as through the use of bolts,clips, or another attachment mechanism. When affixed to the print head150 the gauge 1100 includes a first section 1104 at a first verticalposition Z₁ and a second section 1106 at a second vertical position Z₂.As shown in FIG. 11, the first vertical position Z₁ is vertically higherthan, or above, the second vertical position Z₂. In embodiments, thefirst section 1104 and the second section 1106 can have differentindicia or colors to enhance visual differentiation between the firstand second vertical positions.

In practice, the print head 150 may be moved over the cleaning station110, and the member 610 (e.g., wet wipe member 310, dry wipe member 312,or cap 710) is raised to an initial maximum vertical position. As usedherein, the “maximum vertical position” of a member refers to thevertical position of the top edge 1108 of the member 610 when the member610 is at a set maximum vertical height out of the cleaning stationvessel 314. The print head 150 may be positioned directly over themember 610, or the print head 150 may be located elsewhere over thecleaning station 110 to enable visual comparison of the verticalposition of the member 610 with the gauge 1100. The maximum verticalposition Z_(m) of the member 610 is then adjusted such that the top edge1108 of the member 610 is vertically below or lower than the firstvertical position Z₁. In embodiments, the maximum vertical positionZ_(m) of the member 610 is also greater than or equal to the secondvertical position Z₂. Put another way, the member 610 is adjusted suchthat the maximum vertical position Z_(m) of the member 610 isZ₁>Z_(m)≥Z₂. Adjustments of the maximum vertical position Z_(m) of themember 610 can be made by adjusting an adjustable hard stop, as shownand described herein above, adjusting one or more parameters or settingsof an actuator coupled to the member 610, or by other methods that willbe known to those of skill in the art, depending on the particularembodiment. In embodiments, adjustments can be made using the gauge 1100to any or all of the components of the cleaning station 110.

Having described various sections of a cleaning station 110, a fluidmanagement system suitable for providing cleaning fluid to the cleaningstation 110 and binder material to the print head 150 will now bedescribed in detail.

Fluid Management System

Referring now to FIG. 8 in conjunction with FIG. 1, a fluid managementsystem 800 includes a binder material pathway for providing bindermaterial 500 to a print head 150 and for recycling binder material 500not deposited on build material 400 positioned on the build platform 120and a cleaning fluid pathway for providing cleaning fluid to thecleaning station 110 for cleaning the print head 150 between depositingoperations and recycling and reconditioning cleaning fluid to minimizethe amount of cleaning fluid that is wasted.

In general, the binder material pathway includes a binder reservoir 802that is in fluid communication with the print head 150 and at least onebinder purge bin 302. As depicted in FIGS. 3A and 3B, the cleaningstation 110 includes two binder purge bins 302. The binder purge bins302 may each include an active drain 806, which allows binder flow fromthe binder purge bin 302 into the binder reservoir 802. Further, asshown, the binder purge bins 302 may each include an overflow drain 812disposed on the sidewall of the binder purge bin 302, which releasesbinder from the binder purge bin 302 if a level of binder in the binderpurge bin 302 exceeds a desired binder fluid level. In some embodiments,level sensors may be included to ensure binder fluid level is properlymonitored and maintained.

Referring again to FIG. 8, the binder material pathway enablesrecirculation of the binder material to reduce or even eliminateclogging of the binder material in the nozzles of the print head 150. Inthe binder material pathway depicted in FIG. 8, two binder purge bins302 are included. In embodiments, one of the binder purge bins 302 mayreceive binder material and contaminants discharged from the print head150 via backpressure prior to cleaning of the print head 150 at thecleaning station 110.

In embodiments including multiple binder purge bins, the first binderpurge bin is located upstream from the cleaning station vessel 314 andthe second binder purge bin (binder purge bin 302 in FIGS. 3A and 3B) ispositioned downstream of the cleaning station vessel 314 and the drywipe cleaner section of the cleaning station 110 along a path of theprint head 150. In embodiments, the second binder purge bin ispositioned upstream of the build area in order to receive bindermaterial ejected (i.e., “spit”) from the print head 150 duringpreparation of the print head 150 before printing. The second binderpurge bin 302, in some embodiments, can include a non-porous medium(e.g., thermal, pH, hydrochromic or wax paper, cloth media, etc.) forreceiving a pattern test printed by the print head 150 when the printhead 150 is positioned over the additional binder purge bin 302. Thepattern can be inspected, such as by using a camera configured tocapture an image of the pattern, to determine if the printed pattern issuitable. For example, if the printed pattern matches a predeterminedreference pattern, the printed pattern may be determined to be suitable.As another example, if the printed pattern differs from thepredetermined reference pattern, the printed pattern may be determinedto be unsuitable. In such embodiments, the print head may be preventedfrom supplying binder material to a working surface of the build area,or adjusted prior to supplying the binder material.

The binder material is provided from the binder reservoir 802 to an inkdelivery system 804 which in turn delivers the binder material to theprint head 150. The ink delivery system 804 enables the separation ofstorage of the binder material from the print head 150 and allows forthe binder material to be replaced or refilled while the additivemanufacturing apparatus 100 is actively printing. The print head 150discharges the binder material through nozzles into, for example, thebuild area and the binder purge bins 302.

Binder material discharged into the one or more binder purge bins 302passes through an active drain 806. In the embodiment depicted in FIG.8, the active drain 806 is located at or near a bottom of each of thebinder purge bins 302, to enable the binder material to be recirculatedwithout requiring the accumulation of the binder material in the binderpurge bins 302. In embodiments, the active drain 806 is in fluidcommunication with a pump 808 that actively moves the binder materialfrom the active drain 806 through a filter 810 and back to the binderreservoir 802. The filter 810 may remove contaminants or largeparticles, such as polymers that have agglomerated as a result ofpartial evaporation of the binder material and build material particles,to ensure that the binder material that is returned to the binderreservoir 802 is suitable for recirculation through the binder materialpathway.

As shown in FIG. 8, each binder purge bin 302 further includes anoverflow drain 812 located through a sidewall of the binder purge bin302. In embodiments, the overflow drain 812 is located within the tophalf of the height of the sidewall of the binder purge bin 302. Theoverflow drain 812 is in fluid communication with a waste reservoir 814.Accordingly, in the event that the active drain 806 becomes clogged orbinder material otherwise accumulates to a level greater than or equalto the position of the overflow drain 812, the binder material can bedrained from the binder purge bin 302 and removed from the bindermaterial pathway via the waste reservoir 814. In the event of a clog inthe active drain 806, the binder material removed from the binder purgebin 302 is directed from the overflow drain 812 to the waste reservoir814 so as to minimize the amount of contaminants recirculated throughthe system, although in some embodiments, it is contemplated that theoverflow drain 812 may be in fluid communication with the binderreservoir 802, such as through the filter 810.

In embodiments, the binder material pathway may optionally include anoverflow tank 813 fluidly coupled to the overflow drain 812 of thebinder purge bin 302. The overflow tank 813, when included, is fluidlycoupled to the binder reservoir 802 and the waste reservoir 814. Inembodiments, the overflow tank 813 is coupled to the binder reservoir802 and the waste reservoir 814 through a valve 815, although otherpathways are contemplated. Valve 815 can be, for example, a pinch valve,a three-way valve, or a four-way valve, although other types of valvesare contemplated. It is further contemplated that the overflow tank 813can be fluidly coupled to another part of the main circulation pathinstead of being fluidly coupled to the binder reservoir 802.

In embodiments including the overflow tank 813, binder materialoverflowing from the binder purge bin 302 flows through the overflowdrain 812 into the overflow tank 813. Binder material in the overflowtank 813 is evaluated and, if verified that the binder material in theoverflow tank 813 is still usable, the binder material is returned tothe binder reservoir 802. If, however, the binder material in theoverflow tank 813 is not still suitable for use (e.g., it contains toomany contaminants or does not otherwise meet specifications for use),the binder material is sent to the waste reservoir 814. In embodimentsincluding the valve 815, the valve 815 can be controlled by a computingdevice, such as control system 1000 that is configured to verify thesuitability of the binder material for use and send a signal to thevalve 815 to direct the binder material to the binder reservoir 802 orthe waste reservoir 814.

Turning now to the cleaning fluid pathway depicted in FIG. 8, thecleaning fluid pathway generally includes a cleaning fluid reservoir 816that is in fluid communication with the cleaning station vessel 314 ofthe cleaning station 110. The cleaning fluid pathway enables cleaningfluid to be applied to the print head 150 to fluidize particlesdeposited on the print head 150, such as build material particles andbinder material particles, while further enabling the cleaning fluid tobe recirculated and reconditioned to reduce the amount of cleaning fluidthat is wasted.

In embodiments, the cleaning fluid is provided from the cleaning fluidreservoir 816 through a filter 818 to a pump 820, which in turn deliversthe cleaning fluid to the cleaning station vessel 314 through a cleaningfluid inlet 822. As shown in FIG. 8, the cleaning fluid inlet 822 may bepositioned in the bottom of the cleaning station vessel 314, although inother embodiments, the cleaning fluid inlet 822 may be provided inanother location along one of the sidewalls of the cleaning stationvessel 314. Additionally or alternatively, multiple cleaning fluidinlets 822 may be positioned within the cleaning station vessel 314along with one or more cleaning fluid outlets to enable a directionalflow of cleaning fluid through the cleaning station vessel 314. Thedirectional flow of cleaning fluid can, for example, agitate thecleaning fluid and debris in the cleaning station vessel 314 and preventthe debris from settling at the base of the cleaning station vessel 314where it may clog the active drain. In embodiments, tubes are connectedto one or more cleaning fluid inlets 822 to direct the cleaning fluidwithin the cleaning station vessel 314. It is further contemplated thatthe contents of the cleaning station vessel 314 can be agitated usingultrasonic waves, oscillating or other non-static jets, turbulators orother vortex generators, or the like.

As the cleaning fluid is pumped into the cleaning station vessel 314,the volume of the cleaning fluid accumulates to a fluid level 600 withinthe cleaning station vessel 314. The volume of cleaning fluid is used tosupply cleaning fluid to the wet wipe member 310 and the capping section308, as described hereinabove, and to supply cleaning fluid to the drywipe cleaner section 306 for cleaning the dry wipe member 312 betweenuses. In embodiments, the cleaning fluid inlet 822 can be left open tosimply fill the cleaning station vessel 314. Alternatively, the cleaningfluid inlet 822 can be connected to the cleaning fluid inlets 416 of thewet wipe member 310 which then fills the fluid ports 407 and then fillsthe area between the wiper blades 406. In this setup, cleaning fluid isconstantly fed when the machine is in operation and is then overflowedinto the cleaning station vessel 314.

The cleaning station vessel 314 includes a drain 824 that is in fluidcommunication with the cleaning fluid reservoir 816. The drain 824,which is also depicted in FIGS. 3A and 3B, is positioned within thecleaning station vessel 314 to maintain the fluid level 600 at apredetermined level. Accordingly, when the volume of cleaning fluidrises above the predetermined level, cleaning fluid is drained from thecleaning station vessel 314 via the drain 824 and returned to thecleaning fluid reservoir 816. In one or more embodiments, the drain 824may be an active drain coupled to a pump, or may be a passive drain,which allows the cleaning fluid to pass out of the cleaning stationvessel 314 without the use of a pump or other active mechanism.

In the embodiment shown in FIG. 8, the cleaning station vessel 314further includes an active drain 826 that is in fluid communication withthe waste reservoir 814. The active drain 826 can be activated to allowat least a portion of the cleaning fluid that is in the cleaning stationvessel 314 to be removed from the cleaning station vessel 314 anddirected to the waste reservoir 814. As will be described in greaterdetail below, a portion of the cleaning fluid may be removed from thecleaning fluid pathway via the waste reservoir 814 in response todetermining that the cleaning fluid contains an unsuitable amount ofcontaminants or that the cleaning fluid should otherwise be replaced,either partially or fully.

In various embodiments, the cleaning station vessel 314 further includesa level sensor 828. The level sensor 828 is used to maintain a constantheight of cleaning fluid within the cleaning station vessel 314. Forexample, the level sensor 828 can determine that the fluid level 600 ofthe cleaning fluid is low and, responsive to the determination,additional cleaning fluid can be pumped into the cleaning station vessel314 using the pump 820. The level sensor may be any suitable type ofsensor. In some embodiments, the level sensor comprises a sensor that itis able to withstand submersion within the cleaning fluid. In otherembodiments, the level sensor is not disposed within the cleaning fluid,and can detect the fluid level via other means. For example, a laserlevel sensor may be used. In embodiments, the level sensor 828 may becoupled to a control system 1000 which receives signals from the levelsensor 828 and provides signals to other system components, such as thepump 820 and/or the active drain 826, as will be described in greaterdetail below. Additionally or alternatively, the level sensor 828 mayinclude the fluid level sensors 322 positioned within the overflowvessel 318, as described in accordance with FIG. 3C above. Accordingly,it is contemplated that the fluid level sensors 322 can be incorporatedinto the cleaning fluid pathway, and coupled to the control system 1000,as has been described with respect to the level sensor 828.

In various embodiments, one or more additional components (not shown inFIG. 8) may be included in the fluid management system 800 as part ofone or both of the binder material pathway or the cleaning fluidpathway. For example, additional level sensors, flow sensors, cameras,heaters, cooling units, temperature sensors, pumps, filters, valves, orthe like may be included in the fluid management pathways to enablemonitoring, control, and adjustment of the fluids in the pathways. Suchadditional components may be included in any of a variety of locationswithin the fluid management system 800 and may be communicativelycoupled to the control system 1000. For example, in embodiments, thecleaning fluid path includes a heater to heat the cleaning fluid priorto it entering the cleaning station vessel 314. When included, theheater may be positioned at any of a number of points along the cleaningfluid path, such as between the pump 820 and the cleaning station vessel314, or within the cleaning station vessel 314 or the cleaning fluidreservoir 816.

As another example, in embodiments a three-way or four-way valve may bepositioned within the drain 824 and the cleaning fluid reservoir 816 toredirect a predetermined amount of the cleaning fluid to the wastereservoir 814. Accordingly, in embodiments, the three-way or four-wayvalve may replace or replicate the functionality of the active drain826. Moreover, it is contemplated that one or more on/off valves (e.g.,pinch valves) may be used in place of or in addition to the three- orfour-way valves described herein.

In embodiments, one or more of the pumps described herein, including butnot limited to pump 808 and pump 820, are capable of moving ferrousmetals as well as other types of metals. Moreover, in embodiments, oneor more of the pumps described herein may include a tunable flow rate,such as through flow regulators, which enable the flow rate to be tuned,such as to enable cleaning fluid to be provided to the wet wipe memberat a first flow rate and to the inlet of the cleaning station vessel ata second flow rate.

Having described a fluid management system 800 for use in providingbinder material and cleaning fluid to various components of the additivemanufacturing apparatus 100, and specifically, the cleaning station 110,the binder material and cleaning fluid will now be described in detail.

Binder Materials

In various embodiments, the binder material is a reversible binder. Asdefined herein, a “reversible binder” is intended to denote athermoplastic or thermoset polymer that, during decomposition, is brokendown into oligomers and other molecules that are similar or identical tothe monomers used to derive the polymer. The reversible binder may bepolymerized via radical chain reactions to bond particles and layers ofa powder used to print the article. While many of the embodimentsdescribed below are directed to metal powder, it is contemplated thatother non-metal powders are suitable, for example, for sand, ceramic,and polymer binder jetting.

Although reference is made to a “metal powder” in various embodimentsherein, it is contemplated that the material used to print the articlemay vary depending on the type of the article and the end use of thearticle. In embodiments in which a metal powder is employed, the metalpowder may include nickel alloys, cobalt alloys, cobalt-chromium alloys,cast alloys, titanium alloys, aluminum-based materials, tungsten, steel,stainless steel, or any other suitable material and combinationsthereof.

Following deposition of a layer of the metal powder, the binder materialis selectively deposited into the layer of metal powder in a patternrepresentative of the structure of the article being printed. Accordingto various embodiments, the binder material may include polymers derivedfrom unsaturated monomers. For example, the binder material may includeone or more polymers having the following formulas: (CH₂CHR)_(n), whereR═—H, —OH, phenyl, alkyl, aryl. The binder material may also include oneor more monofunctional acrylic polymers having the formula(CH₂—CR²COOR¹)_(n), where R¹ is an alkyl or aryl, and R² is H or CH₃;di-acrylic polymers having the formula [(CH₂—CR²COO)₂—R^(3]) _(n), whereR² is H or CH₃ and R³ is a divalent hydrocarbon radical; tri-acrylicpolymers having the following formula [(CH₂CR¹COO)₃—R⁴]_(n), where R¹ isH or CH₃ and R⁴ is a trivalent hydrocarbon radical and/or poly(alkylenecarbonates) including co-polymeric alkylene carbonates, such aspoly(ethylene-cyclohexene carbonate) and those having the followingformulas:

By way of example and not limitation, the binder material may includepoly (methyl methacrylate) (PMMA), polystyrene (PS), poly (vinylalcohol) (PVA), polyacrylic acid (PAA), Poly vinyl pyrrolidone (PVP),poly (alkylene carbonates), and polymers derived from hexanedioldiacrylate (HDDA), trimethylolpropane triacrylate (TMPTA), anddiethylene glycol diacrylate (DGD), derivatives of any of the above, orcombinations of the above.

In some embodiments described herein, the binder material furtherincludes one or more fluorescent dyes. The inclusion of the fluorescentdyes enables an otherwise clear binder material (e.g., a binder materialincluding PVA and water) to be detectable under certain lightingconditions, as will be described in greater detail below. In specificembodiments, the fluorescent dyes/pigments should be photochromic dyesthat respond to specific light intensities, for example near IR or UV(including UVA, UVB, or UVC) light. In embodiments including thefluorescent dye, the intensity of the fluorescence is a function of theconcentration of the fluorescent dye. Accordingly, the inclusion of afluorescent dye can provide information regarding where the bindermaterial has been deposited, how much binder material has beendeposited, and/or the extent to which the binder material has cured.Moreover, the fluorescence of the binder material can enable detectionof leaks or spills, fluid management applications, such as monitoringtank levels, binder material concentration, and contamination, and partdetection. Specific embodiments of using the fluorescent dye in processcontrol are provided below.

In various embodiments, the fluorescent dye in the binder material maybe any suitable fluorescent dye that is compatible with the bindermaterial. In some embodiments, the fluorescent dye is not quenched bythe metal powder. Moreover, the fluorescent dye should not negativelyimpact the material properties of the green body, brown body, or finalpart. Examples of fluorescent binders are fluorescent inorganic pigmentsand solid solutions of fluorescent dyes in transparent synthetic resins,polymer encapsulated fluorescent dyes.

Fluorescent pigments are solid solutions of fluorescent dyes. Thesefluorescent dyes may include polyenes, rhodamines, coumarins,naphthalimides, fluoresceins, diazonium salt, acridines, benzoxanthenes,or combinations thereof. The fluorescent color achieved can be from acombination of a single fluorescent dye embedded in a medium (e.g.,polymer or resin carrier) or by combining multiple fluorescent dyes atdifferent ratio. When incorporated in a resin dispersion, it iscontemplated that the dispersion may be water or solvent based. The dyesmay be proteins or non-proteins, and may be organic or synthetic. It iscontemplated that the particular dye selected will vary based on theparticular embodiment employed. Examples of suitable fluorescent dyesare described in PCT Publication WO 03/029340, which is incorporated byreference herein in its entirety.

Various sizes are contemplated for the fluorescent pigment. For example,the fluorescent pigment or fluorescent dye resin may have a typicalaverage particle size from about 0.01 to about 1 μm. The amount offluorescent pigment or fluorescent dye resin may be in the typical rangeof 0.01 to 5% by weight, or from 0.1 to 2% by weight.

The binder material may further include one or more additives thatfacilitate deposition of the binder material into the layer of metalpowder. For example, the binder material may include one or moreadditives such as viscosity modifiers, dispersants, stabilizers,surfactants (e.g., surface active agents) or any other suitable additivethat may facilitate the jettability of the binder material anddeposition of the binder material into the layer of metal powder. Thesurfactants may be ionic (e.g., zwitterionic, cationic, or anionic) ornon-ionic, depending on the properties of the binder material and/or themetal powder.

In some embodiments, the additive(s) may improve the wettability of themetal powder to facilitate coating the metal powder with the bindermaterial. The additive(s) may also modify the surface tension of thebinder material to facilitate jettability of the binder material. Forexample, in embodiments, the binder material is considered jettable ifthe Ohnesorge number (e.g., the ratio of viscous forces to inertial andsurface tension forces) is between approximately 0.01 and approximately2.

In embodiments, the additive(s) may also include a solvent thatdissolves the binder material. The solvent may be aqueous ornon-aqueous, depending on the particular polymers selected and otheradditives that may be in the binder material. The solvent is generallynon-reactive (e.g., inert) such that it does not react with the metalpowder, the polymers in the binder material, or any other additives thatmay be in the binder material. Additionally, the solvent should readilyevaporate after selective deposition of the binder material into thelayer of metal powder to facilitate bonding of the binder-coatedparticles and the printed layers. Example solvents that may be used inthe binder material include, but are not limited to, water, methylenechloride (CH₂Cl₂), chloroform (CHCl₃), toluene, xylenes, mesitylene,anisole, 2-methoxy ethanol, Butanol, diethylene glycol, tetrahydrofuran(THF), methyl ethyl ketone (MEK), trichloroethylene (TCE), or any othersuitable solvent.

The binder material may include the reversible binder, one or moremonomers used to derive the reversible binder, or both. For example, insome embodiments, the reversible binder is polymerized before selectivedeposition into the layer of metal powder. Accordingly, in suchembodiments, the binder material may include the reversible binder as apre-formed, dissolved polymer. The reversible binder may be solubilizedin a suitable solvent to facilitate jettability and deposition into thelayer of the metal powder. Following deposition, the solvent mayevaporate and the reversible binder may coalesce and bond thebinder-coated particles and the printed layers to form the green bodypart.

In other embodiments, the reversible binder is polymerized afterdepositing the binder solution into the layer of metal powder. That is,the reversible binder may be polymerized in situ. For such embodiments,the binder material may include one or more polymerizable monomers(e.g., reactive monomers) that react to form the reversible binder. Inone particular embodiment, the binder material includes the one or morepolymerizable monomers and a suitable solvent. In other embodiments, thebinder material does not include a solvent. Rather, the binder materialmay be a neat liquid of the one or more polymerizable monomers. Once thebinder solution is deposited onto the layer of metal powder, the one ormore polymerizable monomers may be polymerized to form the reversiblebinder within the layer of metal powder to form the printed layer of thegreen body part. In certain embodiments, the binder material may includeinitiators such as, for example, azobis (isobutyronitrile) (AIBN), tofacilitate in situ polymerization of the one or more polymerizablemonomers in the layer of metal powder.

By way of non-limiting example, in some embodiments, the binder materialmay include between about 0.5 weight percent (wt. %) and about 30 wt. %of the polymerized reversible binder or the polymerizable monomers usedto derive the reversible binder in situ. In one embodiment, the bindermaterial include from about 3 wt. % to about 7 wt. % of the polymer orpolymerizable monomers. Additionally, the binder material may includesuitable viscosity modifiers to enable a viscosity of the bindermaterial that is from about 2 centipoise (cP) and about 200 cP. Forexample, depending on the viscosity of the mixture of the solvent andpolymer/polymerizable monomer solution or the neat polymerizable monomersolution, the binder material may have from about 0.1 wt. % to about 15wt. % of a viscosity modifier, such that the viscosity of the bindermaterial is within the desired range for efficient and effectivejettability.

Following deposition of the metal powder and printing of the bindermaterial, the reversible binder is cured to form a layer of the greenbody part. While a portion of the solvent in the binder material may beevaporated during deposition (e.g., printing) of the binder material, acertain amount of the solvent may remain within the layer of metalpowder. Therefore, in certain embodiments, the green body part may bethermally cured at a temperature that is suitable for evaporating thesolvent remaining in the printed layer and allowing efficient bonding ofthe printed layers of the green body part.

In embodiments, the green body part may be cured to allow polymerizationof the polymerizable monomers in the binder material to yield thereversible binder. For example, as discussed above, the reversiblebinder may be polymerized in situ after printing the binder materialinto the layer of metal powder. Following deposition of the bindermaterial, the one or more polymerizable monomers in the binder materialmay be cured to polymerize the one or more monomers and form the printedlayer of the green body part. For example, the printed layers may beexposed to heat, moisture, light, or any other suitable curing methodthat polymerizes the one or more polymerizable monomers in the bindermaterial before the next layer of metal powder is deposited on top ofthe printed layer. In certain embodiments, the binder material mayinclude a radical initiator (e.g., AIBN) to facilitate polymerization ofthe one or more polymerizable monomers. In one embodiment, the one ormore polymerizable selectively deposited may be cured immediately afterforming the printed layer. In other embodiments, the one or morepolymerizable monomers may be cured after a desired number of printedlayers has been formed. Excess metal powder (e.g., the metal powder thatis not bonded by the reversible binder) may be removed after curing toprepare the green body for post-printing processing. After curing, thegreen body may undergo a drying step to remove any solvent and/or othervolatile materials that remain in the green body part. For example, thegreen body may be dried in a vacuum, under an inert atmosphere (e.g.,nitrogen or argon), or air.

Additional details on binder materials suitable for use in theembodiments described herein may be found in U.S. Patent ApplicationPublication No. 2018/0071820 to Natarajan et al., entitled “Reversiblebinders for use in binder jetting additive manufacturing techniques” andfiled on Sep. 9, 2016, the entire contents of which is herebyincorporated by reference. Moreover, it is contemplated that otherbinder materials may be used with the cleaning station and/or additivemanufacturing apparatus described herein, depending on the particularembodiment.

Cleaning Fluids

In various embodiments, the cleaning fluid is compatible with the bindermaterial (e.g., capable of dissolving or otherwise enabling with bindermaterial to be wiped away) and is safe for the components of theadditive manufacturing apparatus 100 (e.g., does not cause the need forexcessive maintenance or cleaning). In some embodiments, such asembodiments in which the binder material is water-based, the cleaningfluid is a water-miscible cleaning fluid.

In various embodiments, the cleaning fluid includes from 0.1 wt. % to 30wt. % of a cleaning agent. For example, the cleaning fluid can includefrom 0.1 wt. % to 30 wt. %, from 0.1 wt. % to 20 wt. %, from 0.5 wt. %to 10 wt. %, from 1 wt. % to 10 wt. %, or from 1 wt. % to 5 wt. % of thecleaning agent. In embodiments, the cleaning agent is an organicsolvent. Suitable organic solvents for use in the cleaning fluid includedimethyl formamide (DMF), dimethyl sulfoxide (DMSO), methylpyrrolidone(NMP), N-N-dimethylacetamide (DMAc), 1,3-dimethyl-2-imidazolidnone(DMI), 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU),ethylene glycol, diethyl glycol, dipropylene glycol dimethyl ether,cyrene, dimethyl isosorbide, propylene glycol, and mixtures thereof. Inparticular embodiments, the cleaning agent is DMF, NMP, DMSO,dipropylene glycol dimethyl ether, cyrene, dimethyl isosorbide, ethyleneglycol, or combinations thereof.

It is contemplated that in some embodiments, the cleaning fluid mayinclude one or more additives, although in other embodiments, thecleaning fluid includes the cleaning agent and water. Accordingly, invarious embodiments, the cleaning fluid includes from 80 wt. % to 99.9wt. % water, from 90 wt. % to 99.5 wt. % water, from 90 wt. % to 99 wt.% water, or from 95 wt. % to 99 wt. % water.

The cleaning fluid of various embodiments has a viscosity that enablesthe cleaning fluid to flow through the cleaning fluid pathway withoutissue. In embodiments, the cleaning fluid has a viscosity of less than10 cP or less than 5 cP at 25° C. For example, the cleaning fluid mayhave a viscosity of from 0.5 cP to 5 cP, 0.5 cP to 3 cP, from 1 cP to 2cP, or from 1 cP to 1.5 cP.

Additionally, or alternatively, the cleaning fluid of variousembodiments has a boiling point that is greater than or equal to theboiling point of water. By having a boiling point that is greater thanor equal to that of water, the cleaning fluid can resist evaporation andkeep the print head 150 moist by preventing the binder material fromdrying. In various embodiments, the cleaning fluid has a boiling pointthat is greater than or equal to 100° C. at 1 atm, greater than or equalto 110° C. at 1 atm, greater than or equal to 125° C. at 1 atm, or evengreater than or equal to 150° C. at 1 atm.

In embodiments, the cleaning fluid is formulated such that the densityof the cleaning fluid is close to the density of water (e.g., 1 g/cm³).In such embodiments, contaminants within the cleaning fluid, such asbinder material and other debris, can be detected based on a change indensity of the cleaning fluid, as will be described in greater detailbelow. Accordingly, in various embodiments, the cleaning fluid has adensity of from 0.900 g/cm³ to 1.400 g/cm³ from 0.900 g/cm³ to 1.200g/cm³ or from 0.900 g/cm³ to 1.100 g/cm³. For example, the cleaningfluid may have a density of from 0.905 g/cm³ to 1.195 g/cm³, from 0.910g/cm³ to 1.175 g/cm³, from 0.950 g/cm³ to 1.150 g/cm³, from 0.905 g/cm³to 1.095 g/cm³, from 0.910 g/cm³ to 1.075 g/cm³, or from 0.950 g/cm³ to1.050 g/cm³.

The cleaning fluid may be heated, such as by a heater positioned alongthe cleaning fluid pathway, although in other embodiments, the cleaningfluid may be applied to the print head 150 at approximately ambienttemperature. As used herein, “ambient temperature” within the machinemay differ from room temperature outside the machine. For example, thetemperature of the machine may be elevated. In other embodiments, thecleaning fluid may be cooled to a temperature below ambient temperaturebefore application to the print head 150. For example, the cleaningfluid may be cooled to a temperature sufficient to cool the print head.Cooling of the cleaning fluid may be accomplished using a coolingapparatus, or simply by recirculation of the cleaning fluid through thecleaning fluid pathway.

As described herein, the cleaning fluid can be applied to the print head150 to dissolve precipitant (e.g., resulting from partial evaporation ofbinder material) and other debris deposited on the print head 150 andwithin the nozzles of the print head 150. Because the cleaning fluid isrecirculated through the system and is also specially formulated to becompatible with the cleaning station 110, the print head 150, and thebinder material ejected from the print head 150, in various embodiments,the cleaning fluid is monitored to determine when the cleaning fluidshould be reconditioned or replaced. An example method 900 of monitoringa status of the cleaning fluid is described in FIG. 9. In someembodiments, the method 900 or similar methods may be used to check the“health” of the cleaning fluid by determining the potency of thecleaning fluid.

In the method depicted in FIG. 9, the method 900 begins by obtaining aninitial value of a physical property of the cleaning fluid (block 902).The physical property can be, for example, a density of the cleaningfluid, a viscosity of the cleaning fluid, a haze measurement, a surfacetension of the cleaning fluid, a color of the cleaning fluid, a pH ofthe cleaning fluid, a conductivity of the cleaning fluid, or afluorescence of the cleaning fluid. The initial value can be obtained inany one of a number of suitable ways, including through the use ofsensors, cameras, or user input into a control system, such as controlsystem 1000. In various embodiments, the initial value can be stored inthe memory of the control system 1000.

Next, the cleaning fluid is circulated through the cleaning fluidpathway for a predetermined amount of time (block 904). In embodiments,circulation of the cleaning fluid through the cleaning fluid pathwayincludes using the cleaning fluid to clean the print head 150. Thepredetermined period of time can vary depending on the particularembodiment. For example, the “predetermined time” may be the samplingrate of an instrument, which would ostensibly yield an effective“continuous” monitoring system. In other embodiments, the predeterminedperiod of time can be a period of 1 minute, 5 minutes, 10 minutes, 30minutes, an hour, 2 hours, or the like. After the passage of thepredetermined period of time, a subsequent value corresponding to thephysical property of the cleaning fluid is obtained (block 906). Thesubsequent value can be determined in the same way as the initial valuewas determined, or by a different method. For example, a user may inputthe initial value for a cleaning fluid when the cleaning fluid isintroduced to the system, but a sensor may be used to obtain subsequentvalues corresponding to the physical property.

Next, an amount of contaminant in the cleaning fluid is estimated basedon the initial value and the subsequent value corresponding to thephysical property of the cleaning fluid (block 908). For example, theinitial and subsequent values may be stored in a look up table (LUT)stored in the memory of the control system 1000 along with an estimatedcontaminant amount. Alternatively, the control system 1000 may performone or more calculations to determine the amount of contaminant in thecleaning fluid. The contaminant may include, for example, dissolved,mixed and/or suspended binder material removed from the print head 150,dissolved, mixed and/or suspended build material (e.g., metal powder),or the like. As used herein, “contaminant” includes, but is not limitedto, precipitant deposited on the print head. In embodiments, thecontaminant comprises polyvinyl alcohol (PVA), polyvinyl pyrrolidone(PVP), polyacrylic acid (PVA), or derivatives thereof. In embodiments,as an alternative to or in addition to determining an estimatedcontaminant amount, an amount of evaporation is estimated. For example,the initial and subsequent values may be stored in a look up table (LUT)stored in the memory of the control system 1000 along with an estimatedevaporation amount. Based on the amount of contaminant in the cleaningfluid, the amount of evaporation of the cleaning fluid, or both, acleaning fluid maintenance process is selected from a plurality ofavailable maintenance processes (block 910). In some embodiments,available maintenance processes may include adding water (or anothersolvent) to the cleaning fluid, replacing a portion of the cleaningfluid containing contaminants with fresh cleaning fluid, replacing amajority of the volume of the cleaning fluid with fresh cleaning fluid,or returning the cleaning fluid containing the contaminants to thecleaning fluid reservoir. Finally, the selected cleaning fluidmaintenance process is performed (block 912).

By way of illustration, the process may include using a density meter toautomatically determine an initial density of the cleaning fluid. Then,after the cleaning fluid has been used for a period of about 15 minutes,the density meter again measures the density of the cleaning fluid.Various time periods are considered suitable and can be tailored basedon print cycles, cleaning cycles, and the like. In one or moreembodiments, the density of the cleaning fluid may be measured asfrequently as every 30 seconds or after 15 minutes, or in a furtherembodiment, density may be measured every 30-60 seconds. The densitymeter transmits both the initial density and the subsequent density ofthe cleaning fluid to the control system 1000, which then estimates anamount of contaminant in the cleaning fluid based on the change indensity. When the estimated amount of contaminant is within a suitablerange, the cleaning fluid recirculated through the cleaning fluidpathway. When the estimated amount of contaminant is moderate, water maybe added to the cleaning fluid, or a portion of the cleaning fluid maybe diverted to the waste reservoir by activating a three-way valve(described above) while new cleaning fluid is added to the cleaningfluid reservoir. Alternatively, when the estimated amount of contaminantis high, the entire volume of the cleaning fluid is diverted to thewaste reservoir and fresh cleaning fluid is added to the cleaning fluidreservoir.

As another example, the process may include using a camera to detect aninitial fluorescence of the cleaning fluid. Then, after the cleaningfluid has been used for a period of about an hour, the camera againmeasures the fluorescence of the cleaning fluid. In embodiments in whichthe binder material includes a fluorescent dye, an increase in thefluorescence of the cleaning fluid can indicate the presence of bindermaterial in the cleaning fluid. The camera transmits both the initialfluorescence and the subsequent fluorescence of the cleaning fluid tothe control system 1000, which then estimates an amount of contaminantin the cleaning fluid based on the change in fluorescence. When theestimated amount of contaminant is within a suitable range, the cleaningfluid recirculated through the cleaning fluid pathway. When theestimated amount of contaminant is moderate, water may be added to thecleaning fluid, or a portion of the cleaning fluid may be diverted tothe waste reservoir by activating a three-way valve (described above)while new cleaning fluid is added to the cleaning fluid reservoir.Alternatively, when the estimated amount of contaminant is high, theentire volume of the cleaning fluid is diverted to the waste reservoirand fresh cleaning fluid is added to the cleaning fluid reservoir.

Although various embodiments are described herein with reference tomeasurement of a single physical property of the cleaning fluid, it iscontemplated that in other embodiments, more than one physical propertycan be monitored and used to determine a cleaning fluid maintenanceprocess to be performed. For example, both density and viscosity can beused to select a cleaning fluid maintenance process. By way of example,the control system 1000 may select a maintenance process that includesadding water to the cleaning fluid based on a change in the density ofthe cleaning fluid, but the control system 1000 may instead select amaintenance process that includes partial replacement of the cleaningfluid or replacement of the majority of the volume of the cleaning fluidwhen the density has decreased too much, indicating that the cleaningfluid may be becoming too diluted to function properly. In embodiments,the selection of the cleaning fluid maintenance process can be based onthe viscosity, the surface tension, or both, of the cleaning fluid.

Control System

Referring now to FIG. 10, FIG. 10 schematically depicts a control system1000 for controlling the components of the cleaning station and thebinder and the cleaning fluid pathways. The control system 1000 iscommunicatively coupled to at least the print head, the pump 808, thepump 820, the active drain 826, and the level sensor 828. Inembodiments, the control system 1000 may additionally be communicativelycoupled to at least one additional sensor 1006, such as a sensor formonitoring one or more physical properties of the cleaning fluid, asdescribed in greater detail above, the actuators 602 a, 602 b coupled tothe wet wipe member 310 and the dry wipe member 312, and the actuator706 coupled to the sponge support 704 or cap 710. In the embodimentsdescribed herein, the control system 1000 comprises a processor 1002communicatively coupled to a memory 1004. The processor 1002 may includeany processing component(s), such as a central processing unit or thelike, configured to receive and execute computer readable and executableinstructions stored in, for example, the memory 1004. In the embodimentsdescribed herein, the processor 1002 of the control system 1000 isconfigured to provide control signals to (and thereby actuate) the printhead 150, the pump 808, the pump 820, and the active drain 826.

In embodiments, the control system 1000 may be configured to receivesignals from one or more sensors of the fluid management system and,based on these signals, actuate one or more of the print head 150, thepump 808, the pump 820, the active drain 826, or other valves, pumps,and drains that may be included in the fluid management system. In someembodiments, the control system 1000 may be configured to receivesignals from one or more additional sensors in the additivemanufacturing apparatus 100 and, based on these signals, actuate one ormore of the actuators 602 a, 602 b coupled to the wet wipe member 310and the dry wipe member 312, and the actuator 706 coupled to the spongesupport 704 or cap 710 to raise and/or lower the components of thecleaning station 110 for use.

In various embodiments, the control system 1000 is configured to receivesignals from and send signals to one or more components describedherein. Accordingly, the control system 1000, in embodiments, can enableone or more of the functions described herein, including, withoutlimitation, movement of any or all of the components of the cleaningstation (e.g., the wet wipe member, the dry wipe member, the cappingsection, and the cleaning station vessel), adjustment of one morecomponents described herein, monitoring the status of binder materialand/or cleaning fluid described herein, monitoring performance of theadditive manufacturing apparatus or any component thereof, measurementsof various components, opening and closing of ports and valves, and thelike. In embodiments, the control system 1000 is configured to controlmotion of the recoat head, the print head, and other components of theadditive manufacturing device described herein.

Moreover, it is contemplated that, although control system 1000 is shownin FIG. 10 as being a single computing device, the control system 1000may be a distributed system that includes multiple computing devicesinterconnected to perform the functions herein.

In the embodiments described herein, the computer readable andexecutable instructions for controlling the additive manufacturingapparatus 100, and particularly, the cleaning station 110 and the fluidmanagement system, are stored in the memory 1004 of the control system1000. The memory 1004 is a non-transitory computer readable memory. Thememory 1004 may be configured as, for example and without limitation,volatile and/or nonvolatile memory and, as such, may include randomaccess memory (including SRAM, DRAM, and/or other types of random accessmemory), flash memory, registers, compact discs (CD), digital versatilediscs (DVD), and/or other types of storage components.

Various methods have been described herein that may be executed by thecontrol system 1000. For example, the monitoring of the status of thecleaning fluid and the selection and implementation of a cleaning fluidmaintenance process, the actuation of the wet wipe member, the dry wipemember, and the sponge, and the ejection of binder material from theprint head may each be performed through execution of computer readableand executable instructions stored in the memory 1004 by the processor1002. It is contemplated that one or more of these functions mayalternatively be performed by one or more additional computing devices,which may be communicatively coupled to the control system 1000. Forexample, the monitoring of the status of the cleaning fluid and theselection and implementation of a cleaning fluid maintenance process maybe performed from a computing device that is separate from, butcommunicatively coupled to, the control system 1000. It is alsocontemplated that additional functions may be performed by the controlsystem 1000 and/or additional computing devices communicatively coupledthereto.

For example, in some embodiments in which the binder material includes afluorescent dye, as described above, the control system 1000 (or othercomputing device communicatively coupled thereto) may determine anamount of cure of the printed part (e.g., through storage and executionof computer readable and executable instructions). A UV camera, avisible or other detection system can be used to detect the fluorescenceof the binder.

During the operation of a an additive manufacturing apparatus, it may bedifficult to assess the quantity, geometric fidelity, and extent of cureof binder deposited into the powder bed. Powder soaked with binder oftenprovides poor visual contrast for reliable optical observation of eachlayer or multiple layers of the green body part. However, the presentembodiments address this problem by including in the binder compositionone or more fluorescent photochromic dyes. After layerwise jettingdeposition into the powder and any subsequent thermal treatment, thesubsequent exposure of the binder-powder surface to UV or otherelectromagnetic radiation will cause the fluorescent dyes to emit light.

Based on the emitted light, a control system including a UV camera canbe used to image each layer of the 3D print. Using the control system,the acquired image(s) at specified time(s) can be compared to theexpected quantity of binder jetted and identify spatial defectsincluding binder jet print head misfires, inaccurate binder quantitydeposition (saturation), as well as insufficient binder cure.

In one embodiment, the control system can determine the presence ofbinder solvent increases the quantum yield of emitted light as comparedto a solvent free sample. If there is solvent in the binder-powderlayer, the control system can pinpoint locations where solvent has notbeen effectively removed. Improper solvent removal may thus indicateareas of incomplete curing. Alternatively, the control system may detectareas of low binder based on the emitted light. This could indicate theclogging of the print head.

After detecting these defects, the control system enables the operatorof the apparatus to troubleshoot or perform diagnostic checks on theadditive manufacturing device, for example, by checking the recoat headand/or print head for clogging issues. In one embodiment, the detectionof a defect may trigger a pattern test to determine if one or more printhead nozzles are clogged.

In one embodiment for monitoring the performance of an additivemanufacturing device using a fluorescent binder, the method compriseexposing at least one layer comprising the fluorescent binder toelectromagnetic radiation. The fluorescent binder includes fluorescentmaterial which emits light in response to the electromagnetic radiation.Next, the method includes recording the emitted light intensity of theat least one layer after exposure, and computing a level of binder,solvent, or both within the layer by utilizing a control system whichcorrelates the recorded emitted light intensity to the level of binder,solvent, or both in the layer versus time. Defects may be located in thelayer when the recorded emitted light intensity deviates from expectedemitted light intensity values, or when the level of binder, solvent orboth deviates from expected levels.

Further aspects of the invention are provided by the subject matter ofthe following clauses:

1. A cleaning station for an additive manufacturing system, wherein thecleaning station comprises: a cleaning station vessel comprising a wetwipe cleaner section and a dry wipe cleaner section downstream of thewet wiper section, wherein: the wet wipe cleaner section comprises a wetwipe member coupled to an actuator, the actuator being operable tovertically raise and lower the wet wipe member into the cleaning stationvessel; and the dry wipe cleaner section comprises a dry wipe membercoupled to an actuator, the actuator being operable to vertically raiseand lower the dry wipe member into the cleaning station vessel, whereinthe wet wipe cleaner section and the dry wipe cleaner section arearranged sequentially such that the wet wipe member is configured toapply cleaning fluid to a print head and the dry wipe member isconfigured to remove excess cleaning fluid from the print head aftercleaning by the wet wipe cleaner section.

2. The cleaning station of any previous clause, further comprising acapping section operable to maintain a print head in a wet state whenthe print head is idle.

3. The cleaning station of any previous clause, wherein the cappingsection comprises a sponge coupled to an actuator, the actuator beingoperable to vertically raise and lower the sponge into the cleaningstation vessel.

4. The cleaning station of any previous clause, wherein at least aportion of the sponge extends above a fluid level of the cleaning fluid.

5. The cleaning station of any previous clause, wherein the cappingsection is coupled to an actuator operable to vertically raise and lowerthe capping section into the cleaning station vessel.

6. The cleaning station of any previous clause, wherein the cleaningstation vessel comprises a plurality of inlet ports located within thecleaning station vessel to circulate the cleaning fluid within thecleaning station vessel and a drain located within the cleaning stationvessel through which contaminants and cleaning fluid exit the cleaningstation vessel.

7. The cleaning station of any previous clause, wherein the cleaningstation vessel is in fluid communication with an overflow vesselcomprising a first fluid level sensor and a second fluid level sensor,wherein cleaning fluid is pumped out of the overflow vessel responsiveto the first fluid level sensor and the second fluid level sensordetecting the cleaning fluid until neither of the first fluid levelsensor and the second fluid level sensor detects the cleaning fluid.

8. A method of cleaning a print head used in an additive manufacturingsystem, the additive manufacturing system comprising a cleaning stationand a build platform, wherein the cleaning station comprises a binderpurge bin and a cleaning station vessel comprising a wet wipe cleanersection, and a dry wipe cleaner section, wherein the cleaning stationvessel comprises cleaning fluid, and wherein the method comprises:passing the print head over the binder purge bin to facilitate dischargeof contaminants from the print head via backpressure; introducing theprint head to the wet wipe cleaner section so that cleaning fluid isapplied to the print head by a wet wipe member; and introducing theprint head to the dry wipe cleaner section so that cleaning fluid isremoved by a dry wipe member and the print head is thereby cleaned.

9. The method of any previous clause, further comprising introducing theprint head to an additional purge bin downstream of the dry wipe cleanersection and upstream of the build platform.

10. The method of any previous clause, wherein the dry wipe member isvertically raised out of the cleaning fluid before completion ofdischarge of contaminants from the print head.

11. The method of any previous clause, wherein the wet wipe member isvertically raised out of the out of the cleaning fluid when discharge ofcontaminants from the print head is complete.

12. The method of any previous clause, wherein excess binder isdischarged into the binder purge bin while a recoat head is operating ina direction supplying build material to a working surface of the buildplatform.

13. The method of any previous clause, wherein the steps of introducingthe print head to the wet wipe cleaner section and introducing the printhead to the dry wipe cleaner section are performed while a recoat headis traveling in a direction from the build platform toward a recoat homeposition.

14. The method of any previous clause, further comprising removingcleaning fluid from the cleaning station vessel if a fluid level ofcleaning fluid exceeds a maximum fluid level.

15. The method of any previous clause, further comprising adjusting oneor more components of the cleaning station, the adjusting comprising:adjusting a vertical position of one or more of a top edge of the wetwipe member and a top edge of the dry wipe member to a position suchthat the one or more of the top edge of the wet wipe member and the topedge of the dry wipe member is vertically lower than a first section ofa height gauge having a first vertical position and vertically higherthan a second section of the height gauge having a second verticalposition; wherein the height gauge is affixed to a print head assemblycomprising the print head.

16. The method of any previous clause, further comprising: prior topassing the print head over the binder purge bin, introducing the printhead to at least one of the dry wipe cleaner section and the wet wipecleaner section to pre-clean the print head.

17. The method of any previous clause, further comprising: introducingthe print head to a purge wipe member after the discharge ofcontaminants from the print head so that binder fluid discharged fromthe print head with the contaminants are wiped from a face of the printhead prior to introducing the print head to the wet wipe cleanersection.

18. A method for storing a print head comprising: applying cleaningfluid to the print head using a wet wipe member; removing cleaning fluidfrom the print head using a dry wipe member; and applying a cover to theprint head to create a non-curing environment around the print head.

19. The method of any previous clause, wherein applying the covercomprises actuating an actuator coupled to a wet sponge to raise the wetsponge within a cleaning station vessel into contact with the printhead.

20. The method of any previous clause, wherein applying the covercomprises bringing the print head into contact with a cleaning vesselcontaining the cleaning fluid to maintain a humidity level between theprint head and the cleaning vessel.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments describedherein without departing from the spirit and scope of the claimedsubject matter. Thus it is intended that the specification cover themodifications and variations of the various embodiments described hereinprovided such modification and variations come within the scope of theappended claims and their equivalents.

1. A cleaning station for an additive manufacturing system, wherein thecleaning station comprises: a cleaning station vessel comprising a wetwipe cleaner section and a dry wipe cleaner section downstream of thewet wiper section, wherein: the wet wipe cleaner section comprises a wetwipe member coupled to an actuator, the actuator being operable tovertically raise and lower the wet wipe member into the cleaning stationvessel; and the dry wipe cleaner section comprises a dry wipe membercoupled to an actuator, the actuator being operable to vertically raiseand lower the dry wipe member into the cleaning station vessel, whereinthe wet wipe cleaner section and the dry wipe cleaner section arearranged sequentially such that the wet wipe member is configured toapply cleaning fluid to a print head and the dry wipe member isconfigured to remove excess cleaning fluid from the print head aftercleaning by the wet wipe cleaner section.
 2. The cleaning station ofclaim 1, further comprising a capping section operable to maintain aprint head in a wet state when the print head is idle.
 3. The cleaningstation of claim 2, wherein the capping section comprises a spongecoupled to an actuator, the actuator being operable to vertically raiseand lower the sponge into the cleaning station vessel.
 4. The cleaningstation of claim 3, wherein at least a portion of the sponge extendsabove a fluid level of the cleaning fluid.
 5. The cleaning station ofclaim 2, wherein the capping section is coupled to an actuator operableto vertically raise and lower the capping section into the cleaningstation vessel.
 6. The cleaning station of claim 1, wherein the cleaningstation vessel comprises a plurality of inlet ports located within thecleaning station vessel to circulate the cleaning fluid within thecleaning station vessel and a drain located within the cleaning stationvessel through which contaminants and cleaning fluid exit the cleaningstation vessel.
 7. The cleaning station of claim 1, wherein the cleaningstation vessel is in fluid communication with an overflow vesselcomprising a first fluid level sensor and a second fluid level sensor,wherein cleaning fluid is pumped out of the overflow vessel responsiveto the first fluid level sensor and the second fluid level sensordetecting the cleaning fluid until neither of the first fluid levelsensor and the second fluid level sensor detects the cleaning fluid. 8.A method of cleaning a print head used in an additive manufacturingsystem, the additive manufacturing system comprising a cleaning stationand a build platform, wherein the cleaning station comprises a binderpurge bin and a cleaning station vessel comprising a wet wipe cleanersection, and a dry wipe cleaner section, wherein the cleaning stationvessel comprises cleaning fluid, and wherein the method comprises:passing the print head over the binder purge bin to facilitate dischargeof contaminants from the print head via backpressure; introducing theprint head to the wet wipe cleaner section so that cleaning fluid isapplied to the print head by a wet wipe member; and introducing theprint head to the dry wipe cleaner section so that cleaning fluid isremoved by a dry wipe member and the print head is thereby cleaned. 9.The method of claim 8, further comprising introducing the print head toan additional purge bin downstream of the dry wipe cleaner section andupstream of the build platform.
 10. The method of claim 8, wherein thedry wipe member is vertically raised out of the cleaning fluid beforecompletion of discharge of contaminants from the print head.
 11. Themethod of claim 10, wherein the wet wipe member is vertically raised outof the out of the cleaning fluid when discharge of contaminants from theprint head is complete.
 12. The method of claim 8, wherein excess binderis discharged into the binder purge bin while a recoat head is operatingin a direction supplying build material to a working surface of thebuild platform.
 13. The method of claim 8, wherein the steps ofintroducing the print head to the wet wipe cleaner section andintroducing the print head to the dry wipe cleaner section are performedwhile a recoat head is traveling in a direction from the build platformtoward a recoat home position.
 14. The method of claim 8, furthercomprising removing cleaning fluid from the cleaning station vessel if afluid level of cleaning fluid exceeds a maximum fluid level.
 15. Themethod of claim 8, further comprising adjusting one or more componentsof the cleaning station, the adjusting comprising: adjusting a verticalposition of one or more of a top edge of the wet wipe member and a topedge of the dry wipe member to a position such that the one or more ofthe top edge of the wet wipe member and the top edge of the dry wipemember is vertically lower than a first section of a height gauge havinga first vertical position and vertically higher than a second section ofthe height gauge having a second vertical position; wherein the heightgauge is affixed to a print head assembly comprising the print head. 16.The method of claim 8, further comprising: prior to passing the printhead over the binder purge bin, introducing the print head to at leastone of the dry wipe cleaner section and the wet wipe cleaner section topre-clean the print head.
 17. The method of claim 8, further comprising:introducing the print head to a purge wipe member after the discharge ofcontaminants from the print head so that binder fluid discharged fromthe print head with the contaminants are wiped from a face of the printhead prior to introducing the print head to the wet wipe cleanersection.
 18. A method for storing a print head comprising: applyingcleaning fluid to the print head using a wet wipe member; removingcleaning fluid from the print head using a dry wipe member; and applyinga cover to the print head to create a non-curing environment around theprint head.
 19. The method of claim 18, wherein applying the covercomprises actuating an actuator coupled to a wet sponge to raise the wetsponge within a cleaning station vessel into contact with the printhead.
 20. The method of claim 18, wherein applying the cover comprisesbringing the print head into contact with a cleaning vessel containingthe cleaning fluid to maintain a humidity level between the print headand the cleaning vessel.